feat(form-builder): form_field_configs relational table + non-validation key split + drop validation_rules JSON columns

apps/portal/src/components/public-form/FieldSectionPriority.vue

@@ -54,7 +54,9 @@ watch(() => props.modelValue, v => {
 }, { deep: true })
 
 const maxPriorities = computed(() => {
-  const raw = props.field.validation_rules?.max_priorities
+  // WS-5b canonicalised the legacy `max_priorities` key to `max_selected`;
+  // the field's cap (if any) is surfaced under `validation_rules.max_selected`.
+  const raw = props.field.validation_rules?.max_selected
   if (typeof raw === 'number' && Number.isFinite(raw) && raw > 0) {
     return Math.min(raw, HARD_CAP)
   }