chore: simayi-approved changes - lint fixes, toolchain improvements, healthz

All changes reviewed and APPROVED in PR #12 (Review ID: 40):
- toolchain_routes: webhook repo/org format compat, content dedup (sha256), closed issue filter
- dispatcher: inform mail crash 误标 done 修复
- ticker: cleanup and improvements
- healthz endpoint
- conftest: integration/e2e deselect markers
- docs: design docs, test-guide updates
- various lint/whitespace fixes across 30 files

src/daemon/health.py

@@ -9,9 +9,9 @@ from __future__ import annotations
 import json
 import logging
 from pathlib import Path
-from typing import Any, Dict
+from typing import Any, Dict, Optional
 
-from src.blackboard.db import get_connection
+from src.blackboard.db import get_connection, init_db
 from src.blackboard.queries import Queries
 
 logger = logging.getLogger("moziplus-v2.health")
@@ -41,6 +41,7 @@ class HealthChecker:
             {"healthy": bool, "zombie": bool, "stale_ticks": int,
              "alert_written": bool, "resolved": bool}
         """
+        db_key = str(db_path)
         result: Dict[str, Any] = {
             "healthy": True,
             "zombie": False,
@@ -57,6 +58,7 @@ class HealthChecker:
         # 用 event count 变化判断是否有真实变更
         conn = queries._conn()
         try:
+            total_events = conn.execute("SELECT COUNT(*) FROM events").fetchone()[0]
             non_tick_events = conn.execute(
                 "SELECT COUNT(*) FROM events WHERE event_type != 'daemon_tick' "
                 "AND event_type != 'agent_zombie_detected'"