feat: Update API endpoint usage in repositories to remove redundant path property

- Refactored multiple repository implementations across client and staff features to directly use endpoint objects without accessing the `path` property.
- Introduced a new `FeatureGate` class for client-side feature gating based on user scopes, allowing for better access control to API endpoints.
- Added `ApiEndpoint` class to represent API endpoints with their paths and required scopes for future feature gating.

apps/mobile/packages/features/staff/profile/lib/src/data/repositories/profile_repository_impl.dart

@@ -14,7 +14,7 @@ class ProfileRepositoryImpl {
   /// Fetches the staff profile from the V2 session endpoint.
   Future<Staff> getStaffProfile() async {
     final ApiResponse response =
-        await _api.get(StaffEndpoints.session.path);
+        await _api.get(StaffEndpoints.session);
     final Map<String, dynamic> json =
         response.data['staff'] as Map<String, dynamic>;
     return Staff.fromJson(json);
@@ -23,7 +23,7 @@ class ProfileRepositoryImpl {
   /// Fetches the profile section completion statuses.
   Future<ProfileSectionStatus> getProfileSections() async {
     final ApiResponse response =
-        await _api.get(StaffEndpoints.profileSections.path);
+        await _api.get(StaffEndpoints.profileSections);
     final Map<String, dynamic> json =
         response.data as Map<String, dynamic>;
     return ProfileSectionStatus.fromJson(json);
@@ -31,6 +31,6 @@ class ProfileRepositoryImpl {
 
   /// Signs out the current user.
   Future<void> signOut() async {
-    await _api.post(AuthEndpoints.signOut.path);
+    await _api.post(AuthEndpoints.signOut);
   }
 }