refactor: split toggleTarget into separate handlers for create and edit forms

Replace conditional setter pattern with explicit if/else branches for editing and creating modes. Handle editForm state updates separately from form state updates to improve code clarity and maintainability.

admin-web/src/features/policies/PoliciesPage.tsx

@@ -140,8 +140,17 @@ export function PoliciesPage() {
   }
 
   function toggleTarget(id: string, editing = false) {
-    const setter = editing ? setEditForm : setForm;
-    setter((value) => ({
+    if (editing) {
+      setEditForm((value) => ({
+        ...value,
+        targetIds: value.targetIds.includes(id)
+          ? value.targetIds.filter((item) => item !== id)
+          : [...value.targetIds, id]
+      }));
+      return;
+    }
+
+    setForm((value) => ({
       ...value,
       targetIds: value.targetIds.includes(id)
         ? value.targetIds.filter((item) => item !== id)