fix(backend): simplify startup to run uvicorn directly with Render's PORT

Procfile

@@ -1 +1,13 @@
-web: cd backend && ALWRITY_ENABLED_FEATURES=podcast python start_alwrity_backend.py --production
+web: cd backend && ALWRITY_ENABLED_FEATURES=podcast python -c "
+import os
+import sys
+# Ensure podcast mode
+os.environ.setdefault('ALWRITY_ENABLED_FEATURES', 'podcast')
+# Set HOST/PORT for Render
+port = os.getenv('PORT', '10000')
+host = os.getenv('HOST', '0.0.0.0')
+print(f'[STARTUP] Starting uvicorn on {host}:{port}', flush=True)
+sys.stdout.flush()
+import uvicorn
+uvicorn.run('app:app', host=host, port=int(port), reload=False)
+"