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.

app/Http/Requests/DeleteMemberRequest.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace App\Http\Requests;
+
+use Illuminate\Foundation\Http\FormRequest;
+use Illuminate\Validation\Rule;
+
+class DeleteMemberRequest extends FormRequest
+{
+    /**
+     * Determine if the user is authorized to make this request.
+     */
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    /**
+     * Get the validation rules that apply to the request.
+     */
+    public function rules(): array
+    {
+        return [
+            'users' => [
+                'required',
+            ],
+            'users.*' => [
+                'required',
+                Rule::exists('users', 'id'),
+            ],
+        ];
+    }
+}