TUI store memory leak: session deletion and message removal leave orphaned data

[Limme-swe]

When a session is deleted in the TUI, only the session entry itself is removed from the store. The associated data in message, part, session_diff, todo, permission, question, and session_status maps are never cleaned up, causing a memory leak that grows with each deleted session.

Similarly, when a message is removed (message.removed event), the corresponding part entries for that message are never deleted.

The web app (packages/app/src/context/global-sync.tsx) already handles this correctly via cleanupSessionCaches() (lines 676-706), but the TUI sync store was never updated to match.

Steps to reproduce:

1. Open TUI, create several sessions with messages
2. Delete sessions
3. Observe that memory usage doesn't decrease — orphaned data remains in the store

Expected behavior:
Deleting a session should clean up all associated keyed data (message, part, session_diff, todo, permission, question, session_status) and remove from fullSyncedSessions. Removing a message should also delete its part entries.

Affected file: packages/opencode/src/cli/cmd/tui/context/sync.tsx

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• TUI store leaks memory on session deletion and message removal #12218: TUI store leaks memory on session deletion and message removal

Feel free to ignore if none of these address your specific case.

[thdxr]

Closing in favor of #20695 where we're collecting all memory-related problems. Please follow that issue for updates.