Fix SQLite migration syntax error in m007

SQLite doesn't support adding multiple columns in a single ALTER TABLE
statement. Split into separate statements for each column.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

migrations.py

@@ -181,12 +181,12 @@ async def m007_add_extra_fields(db):
     to support promo codes and ticket metadata.
     """
     # Add canceled and 'extra' columns to events table
+    # SQLite requires separate ALTER TABLE statements for each column
     await db.execute(
-        """
-        ALTER TABLE events.events
-        ADD COLUMN canceled BOOLEAN NOT NULL DEFAULT FALSE,
-        ADD COLUMN extra TEXT;
-        """
+        "ALTER TABLE events.events ADD COLUMN canceled BOOLEAN NOT NULL DEFAULT FALSE;"
+    )
+    await db.execute(
+        "ALTER TABLE events.events ADD COLUMN extra TEXT;"
     )
 
     # Add 'extra' column to ticket table