Add transfer-questions CLI command for bulk ownership reassignment

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app.py

@@ -1,4 +1,5 @@
 import os
+import click
 from flask import Flask, send_from_directory
 from flask_cors import CORS
 from flask_migrate import Migrate
@@ -87,4 +88,35 @@ def create_app(config_name=None):
         """Health check endpoint"""
         return {'status': 'ok', 'message': 'Trivia Game API is running'}, 200
 
+    @app.cli.command('transfer-questions')
+    @click.argument('username')
+    def transfer_questions(username):
+        """Transfer ownership of ALL questions to the specified user.
+
+        USERNAME is the preferred_username of the target user.
+        """
+        from backend.models import User, Question
+
+        user = User.query.filter_by(preferred_username=username).first()
+        if not user:
+            click.echo(f"Error: No user found with username '{username}'")
+            click.echo("Available users:")
+            for u in User.query.all():
+                click.echo(f"  - {u.preferred_username} (id={u.id}, name={u.name})")
+            raise SystemExit(1)
+
+        count = Question.query.count()
+        if count == 0:
+            click.echo("No questions found in the database.")
+            return
+
+        click.echo(f"This will transfer ownership of {count} question(s) to '{username}' (id={user.id}).")
+        if not click.confirm("Proceed?"):
+            click.echo("Aborted.")
+            return
+
+        Question.query.update({Question.created_by: user.id})
+        db.session.commit()
+        click.echo(f"Successfully transferred {count} question(s) to '{username}'.")
+
     return app