Let the desktop client replace itself, and give the repository one version

Packaging for Windows, and the updater that only exists once something is
packaged. Velopack, win-x64, fed from the project's own forge — never from the
deployment a client signs in to, which is ADR 0011 rule 2 carried over
unchanged and is why the feed address is a constant in the code rather than a
setting. See docs/adr/0012-desktop-distribution-and-updates.md.

**Nothing is ever installed while somebody is using it.** A newer build is found
on a six-hourly pass, downloaded in the background, and then waits — for a
restart the user presses, or for the next launch they were going to do anyway.
That is a policy rather than caution: this application argues at length that
locking keeps shells running, because a lock that destroyed work would stop
being used, and a restart does not keep them. Having taught that, it owes the
user the choice at the one moment it stops being true, and the sentence saying
so counts the shells it would close.

**The version is now derived from the v* tag**, by MinVer, for everything. There
was no version before this — no property anywhere, so every assembly reported
the SDK's 1.0.0 and the API served that string as its serverVersion to every
client that asked. The tag was already the version of record for the container
image; this makes it the version of record full stop. MinVer's failure mode is
answering plausibly rather than failing, and here a wrong version is a client
that never updates, so it is guarded twice: fetch-depth 0 on every checkout, and
a step that fails a tag build when the tag and the computed version disagree.

**The pack id is DodoSSH.Desktop and not DodoSSH**, which is the one decision
here that would have destroyed data. Velopack installs to %LOCALAPPDATA%\<packId>
and removes that whole directory on uninstall, and %LOCALAPPDATA%\DodoSSH is
where ClientPaths keeps the encrypted cache, the outbox of changes not yet
pushed, and the device key. The obvious id would have had the uninstaller
silently delete work the server has never seen — the thing the application
refuses to do without a counted confirmation. Velopack's own advice to move user
data to roaming %APPDATA% is declined for the reason ClientPaths already gives.

**Releases are cut by a person, and CI gains no job that could.** The tempting
argument is that a forge write token is not a signing key. It does not survive
contact with what the token does: Velopack clients trust their feed and do not
verify a package signature when they apply one, so whoever can write a release
can ship an update every install runs. That is the capability ADR 0011 rule 1
puts on a machine which is not a runner, reached through a different door. The
mechanical objection — vpk needs Windows and the runners are Linux — is the
smaller of the two and is recorded beside it, because somebody will fix one and
believe they are done.

Unsigned for now, deliberately and with the cost stated where a user reads it:
SmartScreen warns once per person, on Setup.exe, because Mark-of-the-Web is
applied by the browser that downloaded it. In-app updates are fetched by the
application and applied from a local file, and never trip it.

The banner is a fourth row of the window rather than an overlay. Anything drawn
in the terminal's rectangle is sliced by the native child window that composites
above it — the defect this window has shipped once — and a sibling row is the
arrangement TitleBar and StatusBar already prove works.

----

Three defects surfaced on the way, none of them in the feature being built.

**A settings key absent from the file came back as the CLR default, not the
declared one.** The JSON source generator builds a record through a synthesised
parameterised constructor and assigns every property from its argument array, so
a property initializer runs and is then overwritten by a default for anything the
file did not contain. A settings.json of {} read back a font size of 0, clamped
up to the 8px floor rather than the 13px the renderer draws at. It could not bite
while there was one setting, because that setting was written on every save and
so was never absent; adding a second would have turned automatic update checks
off for every existing profile, silently, the opposite of the documented default.
Reflection-based deserialisation of the same JSON answers correctly, which is why
every way of checking it by hand agrees except the one that ships. The defaults
now live on the constructor parameters, which is the only place the generator
reads them from.

**Declaring a RuntimeIdentifier on the desktop head broke the server's image
build.** It is the obvious way to let a self-contained publish restore under
locked mode, and it writes a net10.0/win-x64 target into the lock file of every
project the head references transitively — including DodoSSH.Contracts and
DodoSSH.Crypto, which the API builds too. The Dockerfile restores those with no
RID and fails NU1004. Found by running docker build rather than by reading. The
RID stays out of the committed state; the two commands that need one ask for it
unlocked, and the release script puts the lock files back.

**A Docker ARG named VERSION silently sets MSBuild's Version.** An ARG is an
environment variable for the rest of the stage, MSBuild reads environment
variables as properties, and property names are case-insensitive. With the
workflow passing main-<short sha> on a main build the publish died with
NETSDK1018 pointing at DodoSSH.Contracts, a project nobody had touched. The build
stage's argument is ASSEMBLY_VERSION now, empty except on a tag build.

All three are in docs/platform-flags.md, which is where the next person will look.

----

Verified: the whole solution builds and restores locked; 289 shell, 93 layout and
54 session tests pass, including the regression test for the settings defect and
a measurement of the banner at the window's minimum width. vpk pack runs end to
end and reports "Verified VelopackApp.Run()" against Program.Main. The API image
builds correctly both as a main build and as a tag build, carrying 1.0.0 and
0.1.0 respectively.

Not verified, and it needs a published release to be: installing, updating and
uninstalling on a real machine. That is Phase 15 of docs/manual-checks.md, and
the pack id and the WebView2 profile fix are reasoned and commented but only
proved by walking it. Two things to watch at the first upload — the reverse
proxy's body-size limit for a 64 MB asset, and whether vpk upload gitea is happy
with Gitea 1.27.1.

src/DodoSSH.Client.App/Program.cs

@@ -1,5 +1,7 @@
 using Avalonia;
 using Avalonia.Media;
+using DodoSSH.Client.Session;
+using Velopack;
 
 namespace DodoSSH.Client.App;
 
@@ -10,11 +12,78 @@ internal static class Program
     /// </summary>
     /// <remarks>
     /// <c>STAThread</c> is required, not decorative: WebView2 checks the apartment state and refuses
-    /// to initialise on an MTA thread. Without it the terminal is simply blank on Windows.
+    /// to initialise on an MTA thread. Without it the terminal is simply blank on Windows. It applies to
+    /// everything below, which is why the Velopack call lives inside this method rather than in an entry
+    /// point of its own.
     /// </remarks>
     [STAThread]
-    public static void Main(string[] args) =>
+    public static void Main(string[] args)
+    {
+        // First, before Avalonia is even configured.
+        //
+        // The installer, the updater and the uninstaller all re-run this executable with arguments that
+        // mean "do the install bookkeeping and stop". Run() is what notices, does it, and exits — so on
+        // those runs nothing below happens at all, and that is the point rather than a side effect:
+        // DodoSshApp.Compose opens the SQLite cache and starts the terminal workspace's listening socket,
+        // and a silent installer run that reached either would be a background process holding the cache
+        // file open during the very file operations the installer is performing.
+        //
+        // There are deliberately no OnFirstRun or OnAfterUpdate hooks. A hook process has no passphrase,
+        // so the cache is bytes it cannot read, and the one thing that would want doing after an update —
+        // a schema migration — already runs on every ordinary launch from MainWindowViewModel.StartAsync,
+        // before unlock and touching no encrypted content.
+        VelopackApp.Build().Run();
+
+        KeepTheWebViewProfileOutOfTheInstallDirectory();
+
         BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
+    }
+
+    /// <summary>
+    /// Puts WebView2's user data folder beside the vault cache instead of beside the executable.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// WebView2 defaults this to a directory next to the host executable. Under a Velopack install that is
+    /// <c>%LOCALAPPDATA%\DodoSSH.Desktop\current\</c>, and <c>current\</c> is <em>replaced</em> by every
+    /// update — so the browser profile would be destroyed on each one, and the first connect afterwards
+    /// would pay a cold WebView2 start: a new user data directory and a fresh process tree, which is the
+    /// slow path <c>TerminalWorkspaceOptions.RendererTimeout</c>'s fifteen seconds was sized for. It would
+    /// land at the exact moment somebody is most ready to believe the update broke the terminal.
+    /// </para>
+    /// <para>
+    /// The profile directory is the right home because Velopack never touches it — the pack id is
+    /// deliberately not <c>DodoSSH</c>, so the install root and <c>ClientPaths.DataDirectory</c> are
+    /// siblings rather than the same folder. See docs/adr/0012-desktop-distribution-and-updates.md.
+    /// </para>
+    /// <para>
+    /// An environment variable rather than the control's own options, because it is read by the WebView2
+    /// loader before any of this application's UI exists, and because it needs no reference to whichever
+    /// WebView package the terminal happens to be hosted by.
+    /// </para>
+    /// </remarks>
+    private static void KeepTheWebViewProfileOutOfTheInstallDirectory()
+    {
+        if (!OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        var folder = Path.Combine(ClientPaths.Default.DataDirectory, "WebView2");
+
+        try
+        {
+            Directory.CreateDirectory(folder);
+
+            Environment.SetEnvironmentVariable("WEBVIEW2_USER_DATA_FOLDER", folder);
+        }
+        catch (Exception exception) when (exception is IOException or UnauthorizedAccessException)
+        {
+            // Left unset, which puts the profile back beside the executable. That is a slow first connect
+            // after each update, not a broken terminal, and refusing to start an SSH client over it would
+            // be the wrong trade.
+        }
+    }
 
     /// <summary>Used by the designer as well as by <see cref="Main"/>.</summary>
     /// <remarks>