Initial commit: DigiServer v2 with Blueprint Architecture

Features implemented:
- Application factory pattern with environment-based config
- 7 modular blueprints (main, auth, admin, players, groups, content, api)
- Flask-Caching with Redis support for production
- Flask-Login authentication with bcrypt password hashing
- API endpoints with rate limiting and Bearer token auth
- Comprehensive error handling and logging
- CLI commands (init-db, create-admin, seed-db)

Blueprint Structure:
- main: Dashboard with caching, health check endpoint
- auth: Login, register, logout, password change
- admin: User management, system settings, theme, logo upload
- players: Full CRUD, fullscreen view, bulk operations, playlist management
- groups: Group management, player assignments, content management
- content: Upload with progress tracking, file management, preview/download
- api: RESTful endpoints with authentication, rate limiting, player feedback

Performance Optimizations:
- Dashboard caching (60s timeout)
- Playlist caching (5min timeout)
- Redis caching for production
- Memoized functions for expensive operations
- Cache clearing on data changes

Security Features:
- Bcrypt password hashing
- Flask-Login session management
- admin_required decorator for authorization
- Player authentication via auth codes
- API Bearer token authentication
- Rate limiting on API endpoints (60 req/min default)
- Input validation and sanitization

Documentation:
- README.md: Full project documentation with quick start
- PROGRESS.md: Detailed progress tracking and roadmap
- BLUEPRINT_GUIDE.md: Quick reference for blueprint architecture

Pending work:
- Models migration from v1 with database indexes
- Utils migration from v1 with type hints
- Templates migration with updated route references
- Docker multi-stage build configuration
- Unit tests for all blueprints

Ready for models and utils migration from digiserver v1

app/extensions.py

@@ -0,0 +1,21 @@
+"""
+Flask extensions initialization
+Centralized extension management for the application
+"""
+from flask_sqlalchemy import SQLAlchemy
+from flask_bcrypt import Bcrypt
+from flask_login import LoginManager
+from flask_migrate import Migrate
+from flask_caching import Cache
+
+# Initialize extensions (will be bound to app in create_app)
+db = SQLAlchemy()
+bcrypt = Bcrypt()
+login_manager = LoginManager()
+migrate = Migrate()
+cache = Cache()
+
+# Configure login manager
+login_manager.login_view = 'auth.login'
+login_manager.login_message = 'Please log in to access this page.'
+login_manager.login_message_category = 'info'