fix(toolchain): 注册 pull_request_sync 和 pull_request_comment event type

Gitea 对 PR branch push 发的是独立事件类型 pull_request_sync，
不是 pull_request + action=synchronize。
同时补注册 pull_request_comment（review comment）。
删除 _handle_pull_request 中永远不会触发的 synchronize 分支。

src/api/toolchain_routes.py

@@ -259,12 +259,10 @@ def _repo_fullname(payload: Dict[str, Any]) -> str:
 
 
 async def _handle_pull_request(payload: Dict[str, Any]) -> None:
-    """处理 pull_request 事件：opened → 通知 reviewer；synchronize → 通知 reviewer 重新 review。"""
+    """处理 pull_request 事件：opened → 通知 reviewer；closed → merge 通知。"""
     action = payload.get("action", "")
     if action == "opened":
         await _handle_pr_opened(payload)
-    elif action == "synchronize":
-        await _handle_pr_synchronize(payload)
     elif action == "closed":
         await _handle_pr_closed(payload)
 
@@ -595,10 +593,12 @@ async def _handle_issue_comment(payload: Dict[str, Any]) -> None:
 
 _EVENT_HANDLERS: Dict[str, Any] = {
     "pull_request": _handle_pull_request,
+    "pull_request_sync": _handle_pr_synchronize,  # Gitea: PR branch push 是独立事件类型
     "pull_request_review": _handle_pull_request_review,
     "pull_request_review_approved": _handle_pull_request_review,
     "pull_request_review_rejected": _handle_pull_request_review,
     "pull_request_review_comment": _handle_pull_request_review,
+    "pull_request_comment": _handle_pull_request_review,  # Gitea: review comment 独立事件类型
     # Gitea v1.23.4 实际发出的 review 子事件（无 _review_ 中间段）
     "pull_request_approved": _handle_pull_request_review,
     "pull_request_rejected": _handle_pull_request_review,
@@ -653,9 +653,11 @@ async def gitea_webhook(
                 return Response(status_code=200, content="duplicate")
 
     # 4. 查找 handler
+    action = payload.get("action", "")
+    logger.info("[WEBHOOK] event=%s action=%s delivery=%s", x_gitea_event, action, x_gitea_delivery)
     handler = _EVENT_HANDLERS.get(x_gitea_event or "")
     if not handler:
-        logger.debug("Unhandled event type: %s", x_gitea_event)
+        logger.info("[WEBHOOK] Unhandled event type: %s", x_gitea_event)
         return Response(status_code=200,
                         content=f"unhandled event: {x_gitea_event}")