Rename company-scoped Users to Members throughout

Complete rename across backend and frontend:
- Controller: Company/Users/UsersController -> Company/Members/MembersController
- Service: UserService -> MemberService
- Requests: UserRequest -> MemberRequest, DeleteUserRequest -> DeleteMemberRequest
- API routes: /api/v1/users -> /api/v1/members (company-scoped only)
- Sidebar menu: "Users" -> "Members"
- Frontend: views/users -> views/members, stores/users -> stores/members
- Router: users.index -> members.index, /admin/users -> /admin/members
- i18n: new "members" section with invitation-related keys
- Tests: UserTest -> MemberTest

Admin/super-admin Users (system-wide user management) remains unchanged.

tests/Feature/Admin/RoleTest.php

@@ -33,7 +33,7 @@ test('create super admin role', function () {
         ],
     ];
 
-    postJson('api/v1/users', $data)
+    postJson('api/v1/members', $data)
         ->assertStatus(201);
 
     $data = collect($data)