feat: integrate Analyst into Plane/Orchestrator pipeline

- Add git fetch+checkout in agent launch cmd (ensures correct branch)
- Add git fetch+checkout in _monitor_agent before commit/push
- Post start comment in Plane when analyst launches
- Post :approved: request comment after analyst completes successfully
- Branch lookup moved before cmd construction for reuse

src/db.py

@@ -28,7 +28,8 @@ def init_db():
             stage TEXT DEFAULT 'created',
             agent_running TEXT,
             created_at TEXT DEFAULT (datetime('now')),
-            updated_at TEXT DEFAULT (datetime('now'))
+            updated_at TEXT DEFAULT (datetime('now')),
+            plane_issue_id TEXT
         );
         CREATE TABLE IF NOT EXISTS agent_runs (
             id INTEGER PRIMARY KEY AUTOINCREMENT,