fix(watchdog): stop phase-machine handoff/gate-token work after SEQUENCE-COMPLETE

Gate-token tracking + handoff pings kept running on the completed phase machine,
churning 0-token gate records every tick. Gate them on `not seq_done`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UWTdUq2bsic7JZGqJp3nD6

agents.py

@@ -968,7 +968,7 @@ def watchdog_loop(cfg_path):
         has_loops = bool(loop_agents(cfg))
         seq_done = (Path(cfg["log_dir"]) / "SEQUENCE-COMPLETE").exists()
 
-        if has_loops:
+        if has_loops and not seq_done:
             handoff_check(cfg)
             gate_token_check(cfg)
         for a in watched(cfg):