chore: synchronize code and database schema (#8577)

* chore: remove default null

null is always the default value if a table column is nullable, and typeorm's
@Column only accepts strings for default.

* chore: synchronize code with database schema

* chore: sync generated migrations with code

packages/backend/src/models/entities/user.ts

@@ -207,7 +207,7 @@ export class User {
 
 	@Column('boolean', {
 		default: false,
-		comment: 'Whether to show users replying to other users in the timeline',
+		comment: 'Whether to show users replying to other users in the timeline.',
 	})
 	public showTimelineReplies: boolean;