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/clip.ts

@@ -37,7 +37,7 @@ export class Clip {
 	public isPublic: boolean;
 
 	@Column('varchar', {
-		length: 2048, nullable: true, default: null,
+		length: 2048, nullable: true,
 		comment: 'The description of the Clip.',
 	})
 	public description: string | null;