add_comment now accepts an optional author (agent role) and POSTs under the matching Plane bot token via _headers_for(), so Plane shows the real author (Analyst/Architect/Developer/Reviewer/Tester/Deployer/Stream) instead of a single shared account. Unknown/empty roles or missing tokens fall back to the shared orchestrator token (autonomy preserved). GET/PATCH (find_issue_id, set_state) are unchanged and stay on the shared token. Call sites in stage_engine, launcher, webhooks/plane and the plane_sync notify helpers now pass author by stage role; stage transitions use stream. Adds tests/test_plane_author.py.
Add 7 optional bot-token fields (plane_bot_analyst..stream) read from the ORCH_PLANE_BOT_* env vars, default empty. Required for per-agent comment authorship; empty values fall back to the shared orchestrator token.
