feat: first-class control-plane lease lifecycle (Closes #601)

Make active leases queryable workflow state with canonical adopt, release,
expire/reclaim, and abandon operations on the #613 control-plane DB substrate.

- lease_lifecycle.py: policy, proof gates, safe_next_action vocabulary
- control_plane_db: schema v3 provenance columns + list/inspect/adopt/abandon
- MCP tools: gitea_*_workflow_lease(s) for list/inspect/adopt/release/expire/abandon/reclaim
- issue_lock_store: sanctioned reclaim of expired author locks (dead pid / missing wt)
- Tests cover lifecycle, foreign steal refusal, allocator compatibility, merger handoff

tests/test_control_plane_db.py

@@ -36,7 +36,7 @@ class ControlPlaneDBTest(unittest.TestCase):
             rows = dict(conn.execute("SELECT key, value FROM schema_meta").fetchall())
         finally:
             conn.close()
-        self.assertEqual(rows["schema_version"], "2")
+        self.assertEqual(rows["schema_version"], "3")
         self.assertIn("DB coordinates", rows["architecture"])
         self.assertIn("bridge", rows["architecture"].lower())