Migrate omsorgapp to browser SPA, add Docker/CI build setup

- omsorgapp: drop Electron, run as a plain Vite/React browser app; refresh
  token moves to an HttpOnly cookie (omsorgCore), CORS added for the new
  browser origin, document download/preview switched to Blob-based browser
  APIs.
- Add Dockerfiles for omsorgCore, omsorgapp, and omsorgWeb, a docker-compose.yml
  wiring Postgres/MySQL/all three apps together, and a Gitea Actions workflow
  that builds and pushes images to the repo's container registry on push to
  main and on version tags.

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

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

@@ -5,6 +5,7 @@ All URIs are relative to http://localhost, except if the operation defines anoth
 | Method | HTTP request | Description |
 | ------------- | ------------- | ------------- |
 | [**apiContractsGet()**](ContractsApi.md#apiContractsGet) | **GET** /api/contracts |  |
+| [**apiContractsIdDelete()**](ContractsApi.md#apiContractsIdDelete) | **DELETE** /api/contracts/{id} |  |
 | [**apiContractsIdGet()**](ContractsApi.md#apiContractsIdGet) | **GET** /api/contracts/{id} |  |
 | [**apiContractsIdPut()**](ContractsApi.md#apiContractsIdPut) | **PUT** /api/contracts/{id} |  |
 | [**apiContractsPost()**](ContractsApi.md#apiContractsPost) | **POST** /api/contracts |  |
@@ -78,6 +79,63 @@ try {
 [[Back to Model list]](../../README.md#models)
 [[Back to README]](../../README.md)
 
+## `apiContractsIdDelete()`
+
+```php
+apiContractsIdDelete($id)
+```
+
+
+
+### Example
+
+```php
+<?php
+require_once(__DIR__ . '/vendor/autoload.php');
+
+
+// Configure Bearer (JWT) authorization: Bearer
+$config = OmsorgCoreClient\Configuration::getDefaultConfiguration()->setAccessToken('YOUR_ACCESS_TOKEN');
+
+
+$apiInstance = new OmsorgCoreClient\Api\ContractsApi(
+    // 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 {
+    $apiInstance->apiContractsIdDelete($id);
+} catch (Exception $e) {
+    echo 'Exception when calling ContractsApi->apiContractsIdDelete: ', $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)
+
 ## `apiContractsIdGet()`
 
 ```php