Add OpenProject Gitea integration plugin

Implements a Gitea integration for OpenProject following the same
patterns as the bundled GitHub and GitLab integrations.

- Webhook endpoint at /webhooks/gitea with HMAC-SHA256 verification
- Handles pull_request and issue_comment events
- Links Gitea PRs to work packages via OP# references or URLs
- Posts journal comments on WPs for PR lifecycle events
- Gitea tab on the work package split view
- V3 API endpoint: GET /api/v3/work_packages/:id/gitea_pull_requests
- Admin settings UI for bot user and webhook secret
- Nightly cron job to clean up unlinked PR records

frontend/module/tab-prs/tab-prs.component.ts

@@ -0,0 +1,69 @@
+//-- copyright
+// OpenProject is an open source project management software.
+// Copyright (C) the OpenProject GmbH
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License version 3.
+//
+// OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+// Copyright (C) 2006-2013 Jean-Philippe Lang
+// Copyright (C) 2010-2013 the ChiliProject Team
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+//
+// See docs/COPYRIGHT.rdoc for more details.
+//++
+
+import { ChangeDetectorRef, Component, Input, OnInit, inject, ChangeDetectionStrategy } from '@angular/core';
+import { WorkPackageResource } from 'core-app/features/hal/resources/work-package-resource';
+import { HalResourceService } from 'core-app/features/hal/services/hal-resource.service';
+import { CollectionResource } from 'core-app/features/hal/resources/collection-resource';
+import { I18nService } from 'core-app/core/i18n/i18n.service';
+import { IGiteaPullRequestResource } from 'core-app/features/plugins/linked/openproject-gitea_integration/typings';
+import { ApiV3Service } from 'core-app/core/apiv3/api-v3.service';
+
+@Component({
+  selector: 'tab-prs',
+  templateUrl: './tab-prs.template.html',
+  host: { class: 'op-prs' },
+  changeDetection: ChangeDetectionStrategy.Eager,
+  standalone: false,
+})
+export class TabPrsComponent implements OnInit {
+  readonly I18n = inject(I18nService);
+  readonly apiV3Service = inject(ApiV3Service);
+  readonly halResourceService = inject(HalResourceService);
+  readonly changeDetector = inject(ChangeDetectorRef);
+
+  @Input() public workPackage:WorkPackageResource;
+
+  public pullRequests:IGiteaPullRequestResource[] = [];
+
+  ngOnInit():void {
+    const basePath = this.apiV3Service.work_packages.id(this.workPackage.id as string).path;
+    const prsPath = `${basePath}/gitea_pull_requests`;
+
+    this.halResourceService
+      .get<CollectionResource<IGiteaPullRequestResource>>(prsPath)
+      .subscribe((value) => {
+        this.pullRequests = value.elements;
+        this.changeDetector.detectChanges();
+      });
+  }
+
+  public getEmptyText():string {
+    return this.I18n.t('js.gitea_integration.tab_prs.empty', { wp_id: this.workPackage.displayId });
+  }
+}