feat: Add optional web interface authentication with session management

Authentication Features:
  - Optional HTTP Basic Auth with session cookies for web interface protection
  - Configurable username/password with session timeout (default: 1 hour)
  - Selective route protection (web interface protected, webhooks/APIs remain public)
  - Authentication status display with logout functionality in web UI
  - Session cleanup and graceful logout with browser re-authentication prompt

  Configuration:
  - WEB_AUTH_ENABLED in .env (default: false - no breaking changes)
  - WEB_AUTH_USERNAME/WEB_AUTH_PASSWORD in .env.secrets
  - WEB_AUTH_SESSION_TIMEOUT configurable (5min-24h range)

  Development Tools:
  - Added debug_tv.py for TV series/episode debugging (series, season, episode levels)
  - Comprehensive episode data inspection with validation and sources breakdown
  - Complements existing debug_movie.py for complete media debugging coverage

  Technical Implementation:
  - SimpleAuthMiddleware with FastAPI integration
  - Session management with automatic cleanup
  - Authentication status API endpoints
  - Responsive CSS styling for auth UI elements
  - JavaScript functions for auth checking and logout

main.py

@@ -15,6 +15,9 @@ from fastapi import FastAPI
 
 # Import configuration first
 from config.settings import config
+
+# Import authentication
+from api.auth import SimpleAuthMiddleware, create_auth_dependencies
 from utils.logging import _log
 
 # Import core components
@@ -172,6 +175,17 @@ def main():
     # Initialize components
     dependencies = initialize_components()
     
+    # Add authentication dependencies
+    auth_deps = create_auth_dependencies(config)
+    dependencies.update(auth_deps)
+    
+    # Add authentication middleware if enabled
+    if config.web_auth_enabled:
+        app.add_middleware(SimpleAuthMiddleware, config=config)
+        _log("INFO", f"Web authentication enabled for user: {config.web_auth_username}")
+    else:
+        _log("INFO", "Web authentication disabled - web interface is public")
+    
     # Store dependencies globally for signal handler access
     signal_handler.dependencies = dependencies