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/typings.d.ts

@@ -0,0 +1,59 @@
+//-- 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 { HalResourceClass } from 'core-app/modules/hal/resources/hal-resource';
+
+export interface IGiteaUserResource {
+  avatarUrl:string;
+  login:string;
+  name:string;
+}
+
+export interface IGiteaPullRequestResource extends HalResourceClass {
+  body?:{
+    format?:string;
+    raw?:string;
+    html?:string;
+  };
+  createdAt?:string;
+  draft?:boolean;
+  gitea_updated_at?:string;
+  gitea_html_url?:string;
+  htmlUrl?:string;
+  id?:number;
+  labels?:Array<{ name:string; color:string }>;
+  merged?:boolean;
+  mergedAt?:string;
+  mergedBy?:IGiteaUserResource;
+  number?:number;
+  repository?:string;
+  state?:string;
+  title?:string;
+  updatedAt?:string;
+  giteaUser?:IGiteaUserResource;
+}