added blueprint and restructured existing routes

app/routes/__init__.py

@@ -0,0 +1,17 @@
+from flask import Blueprint, request, g
+from app import app
+from app.registry.music_provider_registry import MusicProviderRegistry
+
+pl_bp = Blueprint('playlist', __name__)
+
+@pl_bp.before_request
+def set_active_provider():
+    """
+    Middleware to select the active provider based on request parameters.
+    """
+    app.logger.debug(f"Setting active provider: {request.args.get('provider', 'Spotify')}")
+    provider_id = request.args.get('provider', 'Spotify')  # Default to Spotify
+    try:
+        g.music_provider = MusicProviderRegistry.get_provider(provider_id)
+    except ValueError as e:
+        return {"error": str(e)}, 400