Firefly III user API endpoints expose all users' information to any authenticated user (IDOR)

Summary

### Summary

The User management API endpoints (`GET /api/v1/users` and `GET /api/v1/users/{id}`) are accessible to any authenticated user without admin/owner role verification, exposing all users' email addresses, roles, and account status.

### Affected Endpoints

1. **GET /api/v1/users** (UserController::index, line 94) — Lists ALL users with full details. No role check. 2. **GET /api/v1/users/{id}** (UserController::show, line 126) — Shows any user's details by ID. No role check.

### Root Cause (1-of-N Inconsistency)

Other methods in the same controller properly check for the 'owner' role:

- `store()` — `UserStoreRequest::authorize()` checks `auth()->user()->hasRole('owner')` ✓ - `destroy()` — Explicitly checks `$this->repository->hasRole($admin, 'owner')` ✓

But `index()` and `show()` have no role check at all. The route group at `routes/api.php:734-747` has no admin middleware, only the global `auth:api` middleware.

### Exposed Data

The `UserTransformer` (line 40-54) returns: - `email` — user's email address - `role` — user's role (owner/demo) - `blocked` — account blocked status - `blocked_code` — block reason - `created_at` / `updated_at` — timestamps

### Impact

Any authenticated user can: 1. Enumerate ALL user accounts in the instance 2. Harvest email addresses for phishing/social engineering 3. Identify admin/owner accounts by role 4. Determine which accounts are blocked

### Exploitation

```bash # List all users curl -H "Authorization: Bearer <any_user_token>" https://instance/api/v1/users

# View specific user details curl -H "Authorization: Bearer <any_user_token>" https://instance/api/v1/users/1 ```

### Suggested Fix

Add owner role checks to `index()` and `show()`, or restrict the route group with admin middleware:

```php // Option 1: Add check in controller methods public function show(User $user): JsonResponse { if (!$this->repository->hasRole(auth()->user(), 'owner') && auth()->user()->id !== $user->id) { throw new FireflyException('200025: No access to function.'); } // ... }

// Option 2: Add middleware to route group Route::group(['middleware' => ['admin'], ...], ...) ```