refactor: split monolithic main.py into services/ + ui/ modules (improve-maintainability)

- main.py: 4360 → 146 lines (96.6% reduction), entry layer only
- services/: rate_limiter, autostart, persona, connection, profile,
  hotspot, content, engagement, scheduler, queue_ops (10 business modules)
- ui/app.py: all Gradio UI code extracted into build_app(cfg, analytics)
- Fix: with gr.Blocks() indented inside build_app function
- Fix: cfg.all property (not get_all method)
- Fix: STATUS_LABELS, get_persona_keywords, fetch_proactive_notes imports
- Fix: queue_ops module-level set_publish_callback moved into configure()
- Fix: pub_queue.format_*() wrapped as queue_format_table/calendar helpers
- All 14 files syntax-verified, build_app() runtime-verified
- 58/58 tasks complete"

openspec/changes/improve-maintainability/specs/services-connection/spec.md

@@ -0,0 +1,16 @@
+## ADDED Requirements
+
+### Requirement: 连接管理函数迁移至独立模块
+系统 SHALL 将所有 LLM / SD / MCP 连接管理及认证相关函数从 `main.py` 提取至 `services/connection.py`，包括：`_get_llm_config`、`connect_llm`、`add_llm_provider`、`remove_llm_provider`、`on_provider_selected`、`connect_sd`、`on_sd_model_change`、`check_mcp_status`、`get_login_qrcode`、`logout_xhs`、`_auto_fetch_xsec_token`、`check_login`、`save_my_user_id`、`upload_face_image`、`load_saved_face_image`。
+
+#### Scenario: 模块导入成功
+- **WHEN** `main.py` 执行 `from services.connection import connect_llm, connect_sd` 等导入
+- **THEN** 所有函数可正常调用，行为与迁移前完全一致
+
+#### Scenario: 外部依赖通过参数传入
+- **WHEN** `services/connection.py` 中的函数需要访问 `cfg`、`llm`（`LLMService`）、`sd`（`SDService`）、`mcp`（`MCPClient`）
+- **THEN** 这些依赖 SHALL 通过函数参数接收，`services/connection.py` 模块顶层不创建单例实例
+
+#### Scenario: 无循环导入
+- **WHEN** Python 解释器加载 `services/connection.py`
+- **THEN** 不产生 `ImportError` 或循环导入错误