fix(migrations): missing help text and constraint (#9591)

api/src/backend/api/migrations/0063_scan_category_summary.py

@@ -59,7 +59,6 @@ class Migration(migrations.Migration):
                             ("low", "Low"),
                             ("informational", "Informational"),
                         ],
-                        max_length=50,
                     ),
                 ),
                 (

api/src/backend/api/migrations/0064_finding_categories.py

@@ -16,6 +16,7 @@ class Migration(migrations.Migration):
                 blank=True,
                 null=True,
                 size=None,
+                help_text="Categories from check metadata for efficient filtering",
             ),
         ),
     ]