feat: Dashboard数据关联修复 + 通知模板优化 + 工单创建页布局

1. Dashboard: stats新增queryStats查询统计, trend API真实工单趋势数据
2. Layout铃铛: 显示真实待审批工单数量
3. 通知模板优化:
   - 创建工单通知: 含申请人+目标实例+库+SQL摘要
   - 审批通过/拒绝通知: 含审批人+目标实例
   - 执行完成/失败通知: 含执行人+目标实例+库
4. 飞书卡片颜色: 创建=turquoise, 审批=blue, 成功=green, 失败=red
5. 钉钉消息: 添加状态emoji标签(🆕✅❌⚠️)
6. TicketCreatePage: 底部操作栏(SQL检测+提交审批)
7. ticket_executor: 移除aiomysql不支持的read_timeout/write_timeout

Tests: 1057 passed, 17 pre-existing failures (notification 35/35 passed)

backend/tests/test_dashboard.py

@@ -60,10 +60,14 @@ async def test_stats_fields_structure(client: AsyncClient, admin_token: str):
         "instance_online",
         "user_total",
         "queries_today",
+        "query_stats",
     }
     assert set(data.keys()) == expected_keys
     for key in expected_keys:
-        assert isinstance(data[key], int), f"{key} should be int"
+        if key == "query_stats":
+            assert isinstance(data[key], (dict, type(None))), f"{key} should be dict or None"
+        else:
+            assert isinstance(data[key], int), f"{key} should be int"
 
 
 @pytest.mark.asyncio
@@ -166,23 +170,23 @@ async def test_stats_excludes_inactive_users(
 async def test_stats_reflect_queries_today(
     client: AsyncClient, db: AsyncSession, admin_token: str
 ):
-    """Add audit logs with QUERY action and verify queries_today."""
+    """Add query histories and verify queries_today counts from QueryHistory."""
+    from app.models.query_history import QueryHistory
     for i in range(5):
-        log = AuditLog(
+        qh = QueryHistory(
             user_id=1,
-            action="QUERY",
-            target_type="query",
-            detail="test query",
+            username="admin",
+            instance_id=1,
+            instance_name="test",
+            db_type="mysql",
+            database_name="test_db",
+            query_content="SELECT 1",
+            query_type="SELECT",
+            execution_time_ms=100,
+            result_rows=1,
+            is_success=True,
         )
-        db.add(log)
-    # also add a non-QUERY log (should be ignored)
-    non_query = AuditLog(
-        user_id=1,
-        action="LOGIN",
-        target_type="session",
-        detail="login event",
-    )
-    db.add(non_query)
+        db.add(qh)
     await db.commit()
 
     resp = await client.get(BASE, headers=auth_header(admin_token))