Resume the last visited session at launch

[iyernaveenr]

Problem

Launching the app always lands on the workspace home ("Cowork with...") even when the user was in the middle of a conversation. Getting back to it requires finding and clicking the Project in the sidebar on every launch -- unlike editors that reopen where the user left off.

Root cause

The pieces for a resume half-exist: the space store persists activeSpaceId and lastVisitedProjectBySpace, but the runtime project store is not persisted (activeProjectId is null at boot) and the workspace tab resets to its default. The existing fallback effect that activates the last visited Project only runs when the UI is already on a project-scoped tab, which is never the case at boot -- so nothing ever triggers the restore.

Fix

On boot, when the persisted state records a last visited Project for the active Space, open it through the exact same path as clicking it in the sidebar (selectProject: history load, tab choice, achieved handling). Guards keep it polite:

• runs once per renderer boot (module-scoped flag, so sidebar remounts never re-trigger it);
• only from the pristine boot state (default tab and no active Project), so deliberately navigating home later is never hijacked;
• no-ops when there is no last visited entry, the Project is not shown in the nav list (e.g. archived), or on a fresh install.

All inputs to the decision are persisted locally, so the resume starts immediately at mount; the conversation content then loads the same way a sidebar click would load it.

Testing

Verified on Linux desktop across full quit/start cycles: the app reopens directly in the last visited conversation, including after closing via the window button; clicking Home afterwards stays on home (no hijack); a Space with no last visited Project boots to home as before. tsc passes and lint is clean for the changed file.