feat(pos): add PIN auth with JWT, rate limiting, and permission middleware

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pos/app.py

@@ -3,6 +3,11 @@ from flask import Flask
 def create_app():
     app = Flask(__name__)
 
+    # Register blueprints
+    from blueprints.auth_bp import auth_bp
+    app.register_blueprint(auth_bp)
+
+    # Health check
     @app.route('/pos/health')
     def health():
         return {'status': 'ok'}