Refactor: Move cache settings API from /api/user/cache-settings to /dashboard/api/cache-settings and use session-based auth

Fix: Restore missing model_performance, cost_overview, recommendations, and optimization_savings variables

Fix: Call _run_config_migrations from _initialize_database to ensure user_cache_settings table is created

- Clarify cache setting is user-level (not global)
- Rename 'Global Cache Setting' to 'User Default Cache Setting'
- Add detailed cache hierarchy explanation
- Add help text for notify_errors explaining behavior

- Add Enable Prompt Caching toggle at both provider and model levels
- Add detailed help text explaining cache override hierarchy
- Add setCacheSetting function to save cache settings directly from provider page
- Add loadCacheSettings to populate current cache states
- Add isCacheEnabled helper to check cache state with proper priority
- Add toasts for success/error feedback
- Cache hierarchy: Model > Provider > Global (default enabled)

- Added link to /dashboard/cache-settings in account menu
- Users can now access prompt cache settings from the dashboard
- Located between API Tokens and Subscription

- Check if timestamp is string before calling fromisoformat()
- MySQL returns datetime objects directly, SQLite returns strings
- Fixes login error: 'fromisoformat: argument must be str'

- Check user cache settings before enabling prompt caching
- Same pattern as implemented for Claude provider
- Users can disable cache per provider/model
- Fixes issue where other providers didn't respect user cache settings

- Rename from /dashboard/user/cache-settings to /dashboard/cache-settings
- Rename template from user_cache_settings.html to cache_settings.html
- Follows same pattern as other dashboard pages (tokens, rotations, autoselects)
- Still uses logged in user session to determine which user to serve

- Use self.user_id and self.provider_id instead of request object
- Fixes the 'name 'request' is not defined' error in Claude provider
- Cache settings are now properly checked for each user request

- Add user_cache_settings database table
- Add database methods to get/set cache settings
- Add API endpoints for cache management
- Add /dashboard/user/cache-settings page
- Integrate with Claude provider to respect user cache settings
- Allow disabling cache per provider, per model, or globally

- Previous fix had wrong indentation, code was still outside with block
- Now all cursor.execute() and conn.commit() are properly inside context manager
- This will actually fix the 'Cursor is not connected' error

- Move all cursor operations inside the 'with' context manager block
- Connection was being closed before cursor.execute() was called
- Fixes 'Cursor is not connected' error in token usage recording

- Convert datetime objects to ISO format strings before JSON serialization
- Handles both created_at and updated_at datetime fields
- Fixes TypeError when loading /dashboard/providers for database users

- Convert datetime objects to ISO format strings before passing to template
- Fixes TypeError: Object of type datetime is not JSON serializable
- Handles both created_at and last_used datetime fields

- Move analytics initialization to AFTER database config is loaded
- Prevents DatabaseRegistry from creating SQLite singleton before MySQL config is available
- Fixes issue where db was initialized twice (first with defaults, then with config)

- Log database config from aisbf.json at startup
- Convert Pydantic models to dict before passing to DatabaseRegistry
- Fix MySQL password validation (allow empty passwords)
- Add traceback on database init errors

- Log database type and query being executed
- Log settings being saved (first 200 chars)
- Verify save by reading back from database
- Add traceback on errors
- Will help diagnose why settings aren't persisting

- Fix sandbox checkbox loading logic (use === true instead of !== false)
- Add console logging to debug save operations
- Add auto-reload after save to verify changes
- Fixes issue where sandbox mode always saved as true

- PayPalPaymentHandler now reads from admin_settings via get_payment_gateway_settings()
- StripePaymentHandler now reads from admin_settings via get_payment_gateway_settings()
- Remove references to non-existent payment_gateway_config table
- Fixes 'base_url' attribute error in PayPal handler
- All payment gateway configs now stored in database only

- Replace OpenID OAuth2 flow with Billing Agreement API
- Add missing wrapper methods in payment service
- Remove dead old OAuth code
- Fixes 'invalid client_id or redirect_uri' error