Persist verificationId for staff certificates

Add support for verificationId throughout the certificate flow: schema, GraphQL mutations/queries, domain, repositories, service implementation, and UI.

- Backend: add verificationId to Certificate schema and include it in upsert/create mutations; add auth insecureReason notes to related connector operations.
- Data layer: add verificationId parameter to StaffConnectorRepository API and propagation in implementation (SDK call remains commented with FIXME until dataconnect SDK is regenerated).
- Domain: add verificationId field to StaffCertificate (constructor, copyWith, props).
- Certificates flow: create verification via verificationService, pass returned verificationId to upsertStaffCertificate so the verification record is persisted with the certificate.
- UI: update certificate upload page to show existing file path, disable editing of name/issuer/number, rearrange fields, move remove button, change file icon and text style.
- Misc: minor lambda formatting cleanup in benefits mapping.

Note: the generated dataconnect SDK must be refreshed to enable the new .verificationId(...) call (there is a commented FIXME in the connector implementation).

apps/mobile/packages/domain/lib/src/entities/profile/staff_certificate.dart

@@ -19,6 +19,7 @@ class StaffCertificate extends Equatable {
     this.issuer,
     this.certificateNumber,
     this.validationStatus,
+    this.verificationId,
     this.createdAt,
     this.updatedAt,
   });
@@ -56,6 +57,9 @@ class StaffCertificate extends Equatable {
   /// Document number or reference.
   final String? certificateNumber;
 
+  /// The ID of the verification record.
+  final String? verificationId;
+
   /// Recent validation/verification results.
   final StaffCertificateValidationStatus? validationStatus;
 
@@ -79,6 +83,7 @@ class StaffCertificate extends Equatable {
     issuer,
     certificateNumber,
     validationStatus,
+    verificationId,
     createdAt,
     updatedAt,
   ];
@@ -97,6 +102,7 @@ class StaffCertificate extends Equatable {
     String? issuer,
     String? certificateNumber,
     StaffCertificateValidationStatus? validationStatus,
+    String? verificationId,
     DateTime? createdAt,
     DateTime? updatedAt,
   }) {
@@ -113,6 +119,7 @@ class StaffCertificate extends Equatable {
       issuer: issuer ?? this.issuer,
       certificateNumber: certificateNumber ?? this.certificateNumber,
       validationStatus: validationStatus ?? this.validationStatus,
+      verificationId: verificationId ?? this.verificationId,
       createdAt: createdAt ?? this.createdAt,
       updatedAt: updatedAt ?? this.updatedAt,
     );