Keep slash commands visible after New Workspace (#1760)

* fix(app): keep slash commands visible after New Workspace

Repeated returns from the app-wide New Workspace route were using dismissTo with the workspace leaf URL. That updated the root URL without popping the nested host stack, so hidden duplicate workspace deck entries could remain mounted and steal composer popover measurements.

Dispatch a root-stack POP_TO into the host workspace route instead, with a Playwright regression for the slash-command popover.

* test(app): tighten workspace autocomplete regression

Derive the expected deck count from the seeded workspaces and make the duplicate-deck assertion hard. Keep the Expo Router pop hint documented because removing it reproduces the hidden deck entries.

docs/development.md

@@ -76,6 +76,15 @@ workspace for that host after the workspace-selection store hydrates unless the
 host's hydrated workspace list proves that workspace is gone; hosts without a
 remembered workspace go to `open-project`.
 
+When app-wide routes such as `/new` navigate back into a host workspace, use
+`navigateToHostWorkspaceRoute()` instead of calling `router.dismissTo()` with the
+leaf workspace URL. The root stack owns `h/[serverId]`; the host stack owns
+`workspace/[workspaceId]/index`. Repeated global-route hops must `POP_TO` the
+root host route and pass the nested workspace screen, or Expo Router can append
+extra hidden workspace deck entries. Those hidden entries are not harmless:
+composer floating panels can measure against the wrong deck and disappear
+offscreen.
+
 Keep workspace identity and retention outside native-stack `getId`/
 `dangerouslySingular`. Expo Router maps `dangerouslySingular` to React
 Navigation `getId`, and `getId` has broken Android native-stack/Fabric by