Add employee-to-order assignments with FR-EM-3 conflict validation

Adds the Assignment core object (Order x Employee, date range) with full
CRUD, soft-delete/trash integration, and generated API clients.

Layers FR-EM-3 conflict checks onto assignment creation: qualification,
absence/availability, working-hours approximation, cross-order overlap,
and active-contract coverage. Each check's severity (Warning vs. Error)
is configurable at runtime via a new AssignmentValidationSettings
singleton and admin settings panel, instead of being hardcoded - lets
the business tune strictness per check without a redeploy.

Adds a live GET /api/assignments/check endpoint so the create-assignment
dialog can preview conflicts as the user picks employee/dates, before
they hit save, rather than only finding out after submitting.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

omsorgWeb/mitarbeiter-app/api-client-php/docs/Api/TrashApi.md

@@ -6,6 +6,8 @@ All URIs are relative to http://localhost, except if the operation defines anoth
 | ------------- | ------------- | ------------- |
 | [**apiTrashAbsencesGet()**](TrashApi.md#apiTrashAbsencesGet) | **GET** /api/trash/absences |  |
 | [**apiTrashAbsencesIdRestorePost()**](TrashApi.md#apiTrashAbsencesIdRestorePost) | **POST** /api/trash/absences/{id}/restore |  |
+| [**apiTrashAssignmentsGet()**](TrashApi.md#apiTrashAssignmentsGet) | **GET** /api/trash/assignments |  |
+| [**apiTrashAssignmentsIdRestorePost()**](TrashApi.md#apiTrashAssignmentsIdRestorePost) | **POST** /api/trash/assignments/{id}/restore |  |
 | [**apiTrashContractsGet()**](TrashApi.md#apiTrashContractsGet) | **GET** /api/trash/contracts |  |
 | [**apiTrashContractsIdRestorePost()**](TrashApi.md#apiTrashContractsIdRestorePost) | **POST** /api/trash/contracts/{id}/restore |  |
 | [**apiTrashEmployeeFacilityDistancesGet()**](TrashApi.md#apiTrashEmployeeFacilityDistancesGet) | **GET** /api/trash/employee-facility-distances |  |
@@ -139,6 +141,121 @@ void (empty response body)
 [[Back to Model list]](../../README.md#models)
 [[Back to README]](../../README.md)
 
+## `apiTrashAssignmentsGet()`
+
+```php
+apiTrashAssignmentsGet($search): \OmsorgCoreClient\Model\TrashAssignmentResponse[]
+```
+
+
+
+### Example
+
+```php
+<?php
+require_once(__DIR__ . '/vendor/autoload.php');
+
+
+// Configure Bearer (JWT) authorization: Bearer
+$config = OmsorgCoreClient\Configuration::getDefaultConfiguration()->setAccessToken('YOUR_ACCESS_TOKEN');
+
+
+$apiInstance = new OmsorgCoreClient\Api\TrashApi(
+    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
+    // This is optional, `GuzzleHttp\Client` will be used as default.
+    new GuzzleHttp\Client(),
+    $config
+);
+$search = 'search_example'; // string
+
+try {
+    $result = $apiInstance->apiTrashAssignmentsGet($search);
+    print_r($result);
+} catch (Exception $e) {
+    echo 'Exception when calling TrashApi->apiTrashAssignmentsGet: ', $e->getMessage(), PHP_EOL;
+}
+```
+
+### Parameters
+
+| Name | Type | Description  | Notes |
+| ------------- | ------------- | ------------- | ------------- |
+| **search** | **string**|  | [optional] |
+
+### Return type
+
+[**\OmsorgCoreClient\Model\TrashAssignmentResponse[]**](../Model/TrashAssignmentResponse.md)
+
+### Authorization
+
+[Bearer](../../README.md#Bearer)
+
+### HTTP request headers
+
+- **Content-Type**: Not defined
+- **Accept**: `text/plain`, `application/json`, `text/json`
+
+[[Back to top]](#) [[Back to API list]](../../README.md#endpoints)
+[[Back to Model list]](../../README.md#models)
+[[Back to README]](../../README.md)
+
+## `apiTrashAssignmentsIdRestorePost()`
+
+```php
+apiTrashAssignmentsIdRestorePost($id)
+```
+
+
+
+### Example
+
+```php
+<?php
+require_once(__DIR__ . '/vendor/autoload.php');
+
+
+// Configure Bearer (JWT) authorization: Bearer
+$config = OmsorgCoreClient\Configuration::getDefaultConfiguration()->setAccessToken('YOUR_ACCESS_TOKEN');
+
+
+$apiInstance = new OmsorgCoreClient\Api\TrashApi(
+    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
+    // This is optional, `GuzzleHttp\Client` will be used as default.
+    new GuzzleHttp\Client(),
+    $config
+);
+$id = 'id_example'; // string
+
+try {
+    $apiInstance->apiTrashAssignmentsIdRestorePost($id);
+} catch (Exception $e) {
+    echo 'Exception when calling TrashApi->apiTrashAssignmentsIdRestorePost: ', $e->getMessage(), PHP_EOL;
+}
+```
+
+### Parameters
+
+| Name | Type | Description  | Notes |
+| ------------- | ------------- | ------------- | ------------- |
+| **id** | **string**|  | |
+
+### Return type
+
+void (empty response body)
+
+### Authorization
+
+[Bearer](../../README.md#Bearer)
+
+### HTTP request headers
+
+- **Content-Type**: Not defined
+- **Accept**: Not defined
+
+[[Back to top]](#) [[Back to API list]](../../README.md#endpoints)
+[[Back to Model list]](../../README.md#models)
+[[Back to README]](../../README.md)
+
 ## `apiTrashContractsGet()`
 
 ```php