test(bruno): add system settings API tests and update list users test

System Settings Bruno Tests (new):
- bruno/system/get-scan-settings.bru
- bruno/system/update-scan-settings.bru
- Test GET endpoint for retrieving system scan settings
- Test PUT endpoint for updating system scan settings
- Include admin authentication requirements
- Document response structures

List Users Bruno Test (update):
- bruno/user/admin/List Users.bru
- Add max_devices to response documentation
- Add device_count to response documentation
- Update feature descriptions

These Bruno tests provide API contract verification for the new
system settings endpoints and document the enhanced user list response.

bruno/user/admin/List Users.bru

@@ -34,6 +34,8 @@ docs {
   - `last_name` (string): Last name (empty if not set)
   - `role` (string): User role ("user" or "admin")
   - `theme` (string): Theme preference (empty if default)
+  - `max_devices` (integer): Maximum number of devices allowed
+  - `device_count` (integer): Current number of registered devices
   - `created_at` (string): Creation timestamp (ISO 8601)
   - `updated_at` (string): Last update timestamp (ISO 8601)
   
@@ -45,6 +47,7 @@ docs {
   **Features:**
   - Admin-only endpoint with complete user information
   - Returns first_name, last_name, role, theme fields
+  - Includes device limits and current device count
   - Useful for user management interfaces
 }
 
@@ -78,6 +81,8 @@ docs {
   - `last_name` (string): Last name (empty if not set)
   - `role` (string): User role ("user" or "admin")
   - `theme` (string): Theme preference (empty if default)
+  - `max_devices` (integer): Maximum number of devices allowed
+  - `device_count` (integer): Current number of registered devices
   - `created_at` (string): Creation timestamp (ISO 8601)
   - `updated_at` (string): Last update timestamp (ISO 8601)
   
@@ -89,5 +94,6 @@ docs {
   **Enhanced Features:**
   - Now admin-only endpoint (moved from public to protected admin group)
   - Returns complete user profile information including names and role
+  - Includes device limits and current device count for monitoring
   - Useful for comprehensive admin user management
 }