Adds guarded removal for archived sessions that are proven to be exact contiguous subsets of another session.
- New
remove-containedproof-only command with explicit--apply - Requires exact byte containment, archived state, verified fold, current source digest, and unfold proof
- Cleans thread rows, dynamic tools, spawn edges, agent assignment references, and exact global-state references
- Uses source isolation plus SQLite transaction and rollback before commit
- Retains a tombstone and fold manifest for byte-level recovery
- Rejects concurrent global-state changes instead of overwriting them
- Preserves large JSON numbers while updating global state
Also includes Windows durability and source-handle fixes from v0.2.0 follow-up CI.