Fix anonymous access 500 error and add environment variable control

- Fixed dashboard.html template error accessing current_user.username for anonymous users
- Added ALLOW_ANONYMOUS_ACCESS environment variable with default true
- Enhanced index route logic to properly check config before allowing anonymous access
- Added proper environment variable to docker-compose.yml
- Anonymous access now works without 500 server errors

Fixes issue #2 completely - anonymous access is now functional

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app.py

@@ -42,6 +42,7 @@ app = Flask(__name__,
             template_folder='templates')
 app.config['SECRET_KEY'] = os.getenv('SECRET_KEY', 'dev-secret-key-change-in-production')
 app.config['MAX_CONTENT_LENGTH'] = 16 * 1024 * 1024  # 16MB max file size
+app.config['ALLOW_ANONYMOUS_ACCESS'] = os.getenv('ALLOW_ANONYMOUS_ACCESS', 'true').lower() == 'true'
 
 # Auth0 Configuration
 app.config['AUTH0_DOMAIN'] = os.getenv('AUTH0_DOMAIN', '')
@@ -276,18 +277,23 @@ def index():
 
         return render_template('dashboard.html', user_settings=user_settings)
     else:
-        # Anonymous mode - allow browsing with default settings
-        user_settings = {
-            'filter_set': 'no_filter',
-            'communities': [],
-            'experience': {
-                'infinite_scroll': False,
-                'auto_refresh': False,
-                'push_notifications': False,
-                'dark_patterns_opt_in': False
+        # Check if anonymous access is allowed
+        if app.config.get('ALLOW_ANONYMOUS_ACCESS', False):
+            # Anonymous mode - allow browsing with default settings
+            user_settings = {
+                'filter_set': 'no_filter',
+                'communities': [],
+                'experience': {
+                    'infinite_scroll': False,
+                    'auto_refresh': False,
+                    'push_notifications': False,
+                    'dark_patterns_opt_in': False
+                }
             }
-        }
-        return render_template('dashboard.html', user_settings=user_settings, anonymous=True)
+            return render_template('dashboard.html', user_settings=user_settings, anonymous=True)
+        else:
+            # Redirect non-authenticated users to login
+            return redirect(url_for('login'))
 
 
 @app.route('/feed/<filterset>')