Changes for refactor of references view, add unique keys for some tables

References sites table updated so we can filter by site later, added
timestamp to tunes so they can be sorted in certain contexts, enforced
uniqueness on some tables that were causing issues

app/__init__.py

@@ -9,6 +9,7 @@ from app.routes_sub import sub_bp
 from app.routes_sources import sources_bp
 from app.routes_musicians import musicians_bp
 from app.routes_tunings import tunings_bp
+from app.routes_reference_sites import reference_sites_bp
 
 
 def create_app():
@@ -37,6 +38,7 @@ def create_app():
     app.register_blueprint(sources_bp)
     app.register_blueprint(musicians_bp)
     app.register_blueprint(tunings_bp)
+    app.register_blueprint(reference_sites_bp)
 
     # --- Error handlers ---
     from sqlalchemy.exc import IntegrityError