session-scoped composer inserts key on session id alone — carry project/work_dir identity through queued restores #350

Follow-up from #348.

pending_queued_restores and the session-scoped RequestedComposerInsert both key on session_id alone, while composer_drafts keys on (Option, Option) — project work_dir + session id. If two loaded projects ever surface the same session id (a copied project, a duplicated .threadlane state dir), a delayed cancel reply or journaled QueuedEntryCancelled could deliver its staged payload to a same-named session in a different project's draft.

Session ids are per-daemon unique today, so this is defense-in-depth rather than a live bug — but the insert already distinguishes "apply to whatever composer is on screen" (session_id: None) from "wait for this session" (Some), and tightening the key to (work_dir, session_id) aligns it with how drafts are actually stored. Documenting/enforcing global session-id uniqueness would also close it.