* fix(hook): add Copilot session lock detection
Copilot CLI exports no identifying environment variable, so nothing distinguishes a Copilot session from a plain shell. Match ancestor pids against session-state inuse locks to find the live session, and only accept a match when the lock owner still names a copilot process, since locks can outlive their session and pids get reused.
* fix(hook): route annotate-last to the live Copilot session
Under Copilot CLI, annotate-last silently fell back to the default transcript reader and annotated a message from a different tool. Take the Copilot branch when an ancestor process holds a session lock, or when PLANNOTATOR_ORIGIN=copilot-cli is set with the cwd heuristic as fallback, and report origin copilot-cli to the annotate server.
* fix(hook): prefer ancestor lock match in copilot-last
The cwd heuristic can pick a stale session when several exist for one repo. Resolve the session locked by an ancestor copilot process first and keep the heuristic as fallback.
* docs(cli): document copilot-last in help
The subcommand worked but was missing from the top-level usage and the per-subcommand help map.
mararn1618