Add enterprise features: auth, caching, background tasks, OpenAPI, we…

[thorwhalen]

…bhooks, and themes

This commit completes the uf package with production-ready enterprise features:

New Modules (6):

• uf/auth.py: Full authentication system with users, sessions, API keys, and role-based access control
• uf/caching.py: Multi-backend caching (memory, disk) with TTL and LRU eviction
• uf/background.py: Task queue system with worker threads, status tracking, and periodic tasks
• uf/openapi.py: OpenAPI 3.0 spec generation with Swagger UI and ReDoc integration
• uf/webhooks.py: HTTP callback system for function completion events
• uf/themes.py: Complete theming system with 4 built-in themes and dark mode support

Features:

• Authentication: Password hashing (PBKDF2-HMAC-SHA256), session management, API keys
• Caching: @cached decorator, memory/disk backends, statistics
• Background: @background decorator, TaskQueue with workers, PeriodicTask scheduler
• OpenAPI: Auto-generated docs, /docs (Swagger), /redoc, /openapi.json routes
• Webhooks: @webhook decorator, retry logic, event filtering
• Themes: LIGHT_THEME, DARK_THEME, OCEAN_THEME, SUNSET_THEME, toggle support

Updated:

• uf/init.py: Export 115+ functions/classes from 19 modules

New Examples:

• examples/ultimate_showcase.py: 550+ line comprehensive demo of ALL features
  • Async functions with timeout/retry
  • Pydantic model integration
  • Result rendering (tables, charts)
  • Authentication (3 test users)
  • Background tasks
  • Caching
  • OpenAPI/Swagger docs
  • Webhooks
  • Field dependencies
  • Rate limiting
  • Function grouping
  • Theme customization

The uf package is now feature-complete with everything needed for production web UIs from Python functions.