refactor(form-field): extract legacy conditional_logic shape normaliser

Three byte-identical copies of `normaliseLegacyGroupShape` lived in
FormFieldService, StoreFormFieldRequest, and UpdateFormFieldRequest.
WS-5d (form_fields.options) would have been the fourth copy. Hoist
the helper to a single public static on FormFieldConditionalLogicService
and have all three call sites delegate.

Implementation:

  - `FormFieldConditionalLogicService::normaliseLegacyShape(array)` —
    pure recursive passthrough. Translates the ARCH §8 JSON group shape
    (`{"all": [...]}` / `{"any": [...]}`) into the service's internal
    `{"operator", "children"}` form. Does NOT validate; malformed shapes
    return as-is and surface downstream as
    `InvalidConditionalLogicSpecException` from `assertSpecsValid`.
  - Group operator catalogue sourced from
    `FormFieldConditionalLogicGroupOperator::values()` instead of an
    `['all', 'any']` literal — single source of truth for future
    operator additions.
  - All three call sites switched to the static method. The two
    FormRequests reach it via the existing `use` import; FormFieldService
    sits in the same namespace.

Behaviour preserved exactly:

  - Existing FormFieldApiTest (cyclic logic rejection),
    FormFieldStrictConditionalLogicRequestTest (strict-validator
    rejection paths), and FormFieldConditionalLogicServiceTest
    (service-level paths) all green without modification.

New unit tests pin the passthrough contract (8 tests):

  - Valid ALL / ANY translations
  - Recursive nested-group translation (depth 2)
  - Internal shape unchanged
  - Condition leaf passthrough
  - Unknown group key (`xor`) returned unchanged for downstream
    `assertSpecsValid` to reject
  - Empty array unchanged
  - Non-array children stripped silently

Tests: 1150 → 1158 green (3110 → 3124 assertions).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

api/app/Services/FormBuilder/FormFieldService.php

@@ -367,44 +367,7 @@ final class FormFieldService
             $rootGroup = $raw;
         }
 
-        return [$this->normaliseLegacyGroupShape($rootGroup), true];
-    }
-
-    /**
-     * @param  array<string, mixed>  $node
-     * @return array<string, mixed>
-     */
-    private function normaliseLegacyGroupShape(array $node): array
-    {
-        if (isset($node['field_slug'])) {
-            return $node;
-        }
-
-        if (isset($node['operator'], $node['children']) && is_array($node['children'])) {
-            $children = [];
-            foreach ($node['children'] as $child) {
-                if (is_array($child)) {
-                    $children[] = $this->normaliseLegacyGroupShape($child);
-                }
-            }
-
-            return ['operator' => $node['operator'], 'children' => $children];
-        }
-
-        foreach (['all', 'any'] as $candidate) {
-            if (isset($node[$candidate]) && is_array($node[$candidate])) {
-                $children = [];
-                foreach ($node[$candidate] as $child) {
-                    if (is_array($child)) {
-                        $children[] = $this->normaliseLegacyGroupShape($child);
-                    }
-                }
-
-                return ['operator' => $candidate, 'children' => $children];
-            }
-        }
-
-        return $node;
+        return [FormFieldConditionalLogicService::normaliseLegacyShape($rootGroup), true];
     }
 
     /**