Give the user menu one door into settings instead of three

Settings, Vaults and Preferences all opened the same full-window settings mode
and differed only in which of its seven pages they landed on. SettingsNav, which
lists every one of those pages including Vaults and Preferences, is on screen the
whole time you are in there — so two of the three rows were deep links into a
place the third one opens. They saved one click and cost a menu that read as
though it offered three destinations.

It was three rows for a reason that had stopped applying. Until v5c, "Settings"
and "Preferences" were two doors onto the same bare Preferences screen, and
splitting them was the fix for something real; Vaults arrived beside them when
VaultsScreen became a settings page too. Folding those two back in is not a
return to that state. They are pages now, with a rail of their own, and what a
menu at the foot of the nav rail is for is getting into settings at all.

Nothing became unreachable — both are one click deeper, from the rail that was
always going to be the way to them.

◆ WHAT STAYS, AND WHY IT IS NOT THE SAME ARGUMENT.

Logout stays and still lands on the Account page rather than on General, because
its confirmation card is drawn inline on that one page while the vault is
unlocked; arming it from anywhere else would raise a card nobody could see. The
vault switches and New vault above the divider stay too — neither is a page of
the settings mode, and the switches have no other home.

◆ THE ROWS ARE REMOVED FROM THE MARKUP, NOT UNWIRED.

NavRailTests asserts their absence rather than only asserting that Settings still
works, because the failure that guards against is silent: a row left in the
markup with its handler deleted is a menu entry that does nothing when pressed,
which reads as a broken application rather than a tidied menu. The helper it
asserts through excludes the vault switches by their data context and not by
their label — a vault is free to be called "Vaults", and a test that a menu entry
is absent must not be defeatable by what somebody named a vault.

Two facts go, one comes back plus the absence check; the layout suite is 166.

Manual check 1.8 walked a reader through all three rows in turn and now walks
them through the one, then through SettingsNav's seven — which is where the two
went. design-import-gaps.md gains a v5c-5 section rather than an edit to the v5c
table: what that table records is what shipped in that pass, and it did.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/manual-checks.md

@@ -118,15 +118,17 @@ view models — this check is the version with a real connection on the end of i
 
 ### 1.8 Entering and leaving settings mode
 
-From HOSTS, press the user chip at the foot of the nav rail and choose **Settings**. Then repeat from a
-fresh open, choosing **Vaults**, and again choosing **Preferences**.
+From HOSTS, press the user chip at the foot of the nav rail and choose **Settings** — which is the menu's
+only way in now; the Vaults and Preferences rows beside it were folded back into it, because all three
+opened this same mode and differed only in which page they landed on.
 
-**Pass:** each of the three swaps the whole window's chrome — the titlebar becomes the 53px "Back to
-application" bar, the ordinary nav rail is replaced by the 340px SettingsNav, and the status bar and the
-update banner (if either was showing) are both gone. **Settings** lands on General; **Vaults** and
-**Preferences** land on their own pages, each lit in SettingsNav's own list — General/Vaults/Account under
-SETTINGS, Security/Preferences/Groups/Tags under CUSTOMIZE, Logout pinned below both. Click every one of the
-seven rows in turn: each swaps the content column without leaving settings mode or touching the titlebar.
+**Pass:** it swaps the whole window's chrome — the titlebar becomes the 53px "Back to application" bar, the
+ordinary nav rail is replaced by the 340px SettingsNav, and the status bar and the update banner (if either
+was showing) are both gone. It lands on **General**, with SettingsNav's own list beside it —
+General/Vaults/Account under SETTINGS, Security/Preferences/Groups/Tags under CUSTOMIZE, Logout pinned below
+both. Click every one of the seven rows in turn: each swaps the content column without leaving settings mode
+or touching the titlebar, and Vaults and Preferences are among them — which is the whole reason the popover
+no longer carries its own rows for those two.
 
 Now open a terminal, leave it showing, and open Settings from the user chip again. Press **Back to
 application** — or, without touching anything else, press Esc.
@@ -134,7 +136,8 @@ application** — or, without touching anything else, press Esc.
 **Pass:** both return to exactly the screen that was showing before Settings was opened — the terminal,
 still running, rather than HOSTS or anywhere else. Switching between settings pages first (General → Vaults
 → Preferences) does not change what "back" goes back to; only the screen open the moment Settings was
-**first** entered does.
+**first** entered does. The other doors into this mode — the palette, and the Preferences page's own two
+importer rows — behave the same way, so the popover having one row rather than three changes nothing here.
 
 **Failure means:** a return to HOSTS regardless of where Settings was opened from is
 `MainWindowViewModel.settingsReturnScreen` being recaptured on every `EnterSettings` call rather than only on