feat(scheduled-tasks): 新增 HTML 页面定时任务(生成/预览/收藏/技能)

后端:
- 新增 task_kind=html_page 任务类型,与普通定时任务并存,配置存 execution_context(无需迁移)
- 执行流水线:智能体检索数据 -> 选定模型渲染 HTML -> 清洗/校验 -> 失败自动修复 -> 完整性闸门(缺 doctype/html/head/body/title 或残留脚本即失败) -> 归档 index.html -> 落库
- 新增 scheduled_html_pages / html_page_favorites 表与 store;收藏去重(不可重复)、可删除、收藏时提取可复用风格
- HTML 预览接口(鉴权 + 公开)、收藏接口
- 渲染注入已启用的 HTML 技能(metadata.kind=html_page);全程使用用户所选模型,去除硬编码 GLM-5
- 定时任务跳过 TitleMiddleware,避免标题生成回退默认模型

前端:
- 创建/编辑弹窗增加任务类型与 HTML 配置(页面要求/限制/参考收藏页/模型下拉)
- 运行详情页与公开页 iframe 沙箱预览 HTML;收藏按钮(已收藏禁用)
- 参考收藏页可选可删

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

offline-backend-20260512/backend/packages/harness/deerflow/agents/lead_agent/agent.py

@@ -280,8 +280,14 @@ def _build_middlewares(
     if resolved_app_config.token_usage.enabled:
         middlewares.append(TokenUsageMiddleware())
 
-    # Add TitleMiddleware
-    middlewares.append(TitleMiddleware(app_config=resolved_app_config))
+    # Add TitleMiddleware — but skip it for scheduled runs. Each scheduled run
+    # executes on a throwaway thread whose title is never shown to a user, and
+    # generating one would fire an extra LLM call on the *default* model
+    # (config.title.model_name is usually unset → models[0]), which is not the
+    # model the task selected. Skipping it keeps scheduled/HTML runs on exactly
+    # the chosen model.
+    if not cfg.get("is_scheduled_run", False):
+        middlewares.append(TitleMiddleware(app_config=resolved_app_config))
 
     # Add MemoryMiddleware (after TitleMiddleware) — skip in bootstrap mode (agent creation flow)
     memory_injection_enabled = cfg.get("memory_injection_enabled", True)