TUI Plugin Sharing 4 - cover remote plugin catalog flows (#26704)

Remote plugin catalogs now span workspace, shared, and local sources, so
their TUI behavior needs focused regression coverage across loading,
navigation, actions, and refreshes.

This PR:

- Covers product labels and rendered loading/error states for Workspace,
Shared with me, Shared with me (link), and Local tabs, including tab
persistence across refresh and detail navigation.
- Covers remote/local deduplication, Installed-tab remote detail
routing, marketplace load-error handling, and disabled install/uninstall
navigation.
- Adds a full detail snapshot for local shared-plugin metadata plus
focused snapshots for marketplace labels and admin-disabled status.
- Verifies shared plugins remain eligible for mentions and successful
uninstalls trigger a catalog refresh.

codex-rs/tui/src/tui.rs

@@ -60,6 +60,8 @@ mod frame_requester;
 mod job_control;
 mod keyboard_modes;
 mod terminal_stderr;
+#[cfg(test)]
+pub(crate) mod test_support;
 
 /// Target frame interval for UI redraw scheduling.
 pub(crate) const TARGET_FRAME_INTERVAL: Duration = frame_rate_limiter::MIN_FRAME_INTERVAL;