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-scheduler/spec.md

@@ -0,0 +1,16 @@
+## ADDED Requirements
+
+### Requirement: 自动调度器函数迁移至独立模块
+系统 SHALL 将调度器相关的状态变量和函数从 `main.py` 提取至 `services/scheduler.py`，包括：`_scheduler_next_times`、`_auto_log`（列表）、`_auto_log_append`、`_scheduler_loop`、`start_scheduler`、`stop_scheduler`、`get_auto_log`、`get_scheduler_status`、`_learn_running`、`_learn_scheduler_loop`、`start_learn_scheduler`、`stop_learn_scheduler`。
+
+#### Scenario: 调度器启停正常工作
+- **WHEN** `start_scheduler(...)` 被调用并传入合法参数
+- **THEN** 调度器线程 SHALL 正常启动，`get_scheduler_status()` 返回运行中状态
+
+#### Scenario: 日志追加线程安全
+- **WHEN** 多个自动化任务并发调用 `_auto_log_append(msg)`
+- **THEN** 日志条目 SHALL 正确追加，不丢失和乱序
+
+#### Scenario: engagement 通过回调写日志
+- **WHEN** `services/engagement.py` 中的函数需要写日志时
+- **THEN** SHALL 通过 `log_fn` 参数（由 `scheduler.py` 传入 `_auto_log_append`）写入，不直接导入 `scheduler.py`