fix: WYSIWYG editor, content generation, and writing assistant bug fixes

- Fix text selection menu not showing: wire contentRef via inputRef on multiline TextField
- Fix blog title not truncating: add min-w-0 for flex item overflow
- Fix outline generation 500: escape curly braces in f-string prompt template
- Fix content generation 'NoneType not callable': replace SessionLocal() with get_session_for_user(), add db param to MediumBlogGenerator, fix signature mismatch in database_task_manager
- Fix writing assistant suggest 500: add auth + user_id to API endpoint and service, replace sync requests with httpx.AsyncClient
- Fix hallucination detector 404: explicitly include router in main.py and app.py
- Fix missing error_data in task failure responses
- Hide CopilotKit web inspector button
- Remove hardcoded fallback suggestions from SmartTypingAssist
- Fix stale closure refs in SmartTypingAssist handleTypingChange
- Add two-column editor layout, stats bar, section hover menu
- Various subscription, billing, and research module improvements

backend/services/subscription/usage_tracking_modules/__init__.py

@@ -0,0 +1,21 @@
+"""
+Usage tracking modules package.
+Split from the monolithic usage_tracking_service.py for better maintainability.
+"""
+
+from .historical_usage import get_all_historical_usage, get_current_period_usage, get_usage_for_period
+from .usage_stats import get_user_usage_stats
+from .usage_trends import get_usage_trends
+from .limits_enforcement import enforce_usage_limits
+from .alerts import check_usage_alerts, create_usage_alert
+
+__all__ = [
+    'get_all_historical_usage',
+    'get_current_period_usage',
+    'get_usage_for_period',
+    'get_user_usage_stats', 
+    'get_usage_trends',
+    'enforce_usage_limits',
+    'check_usage_alerts',
+    'create_usage_alert',
+]