Clear the SSH gate: window-change reaches the remote, and licence as MIT

Licence is MIT, set solution-wide rather than only on the packable project:
DodoSSH.Contracts is published so clients can build against it, and a
package with no licence expression is one a corporate policy scanner
rejects outright.

The SSH.NET spike is the M1 client gate and it passes. SSH.NET 2025.1.0
exposes ShellStream.ChangeWindowSize, but a method existing is not the
remote observing it, so the tests read `stty size` back from a real sshd
after resizing rather than asserting the call did not throw. Repeated
resizes each take effect too, which matters because dragging a window edge
produces a stream of them. The IChannelSession fallback is not needed.

Also verified against a real sshd: password and public-key auth, that the
host key arrives as a raw blob we can fingerprint ourselves rather than
reading SSH.NET's MD5 property, and that refusing the key via CanTrust
actually aborts the connection -- without which the TOFU dialog would be
decoration.

Kept as a permanent suite, not deleted after the spike. An upgrade that
silently stopped sending the request would present as wrapped output only
after a resize, which is easy to misattribute to the terminal emulator.

Two bugs in the test itself, both worth naming because either would have
been read as "resize does not work":

- A PTY emits CRLF, and the anchored regex rejected the CR. The output
  visibly contained `24 80` while the match failed.
- Each read can begin with output still buffered from the previous command,
  including its size line. Taking the first match would have reported the
  pre-resize size.

platform-flags.md now records window-change as resolved rather than
unverified -- a stale flag is worse than none -- plus the three real SSH.NET
limits found on the way: ShellStream does not override ReadAsync so every
idle session parks a pool thread, one connection cannot serve both
SshClient and SftpClient, and agent forwarding needs an upstream change.

Directory.Build.props

@@ -37,6 +37,13 @@
     <Company>DodoTech</Company>
     <Product>DodoSSH</Product>
     <NeutralLanguage>en</NeutralLanguage>
+    <Copyright>Copyright (c) 2026 Jaap-Jan de Wit (DodoTech)</Copyright>
+    <!--
+      Set solution-wide rather than only on the packable project. DodoSSH.Contracts is
+      published to GitHub Packages so clients can build against it, and a package without a
+      licence expression is one a corporate consumer's policy scanner rejects outright.
+    -->
+    <PackageLicenseExpression>MIT</PackageLicenseExpression>
   </PropertyGroup>
 
   <ItemGroup Label="Analyzers">