feat: 集成Piper自建TTS并增加朗读回退

server/app.py

@@ -11,6 +11,7 @@ from server.auth import admin_required, authenticate, create_user, login_require
 from server.db import BASE_DIR, get_db, init_db
 from server.entries_api import entries_bp
 from server.settings_api import settings_bp
+from server.tts_api import tts_bp
 from server.vocab_api import vocab_bp
 
 
@@ -28,6 +29,7 @@ def create_app():
     app.register_blueprint(entries_bp)
     app.register_blueprint(vocab_bp)
     app.register_blueprint(settings_bp)
+    app.register_blueprint(tts_bp)
 
     @app.post("/api/register")
     def register():