feat(jenkins): add Jenkins CI/CD Platform Cloudron package

- Complete Jenkins package with Java 17 and WAR file download
- Proper CloudronManifest.json with correct metadata
- Custom start.sh script with Jenkins configuration
- Health check endpoint configured for /login
- Follows KNELCloudron- naming convention
- Added comprehensive packaging shortlist with 56 applications prioritized by phase

CloudronPackages/Jenkins/nginx.conf

@@ -0,0 +1,26 @@
+user  cloudron;
+worker_processes  auto;
+
+error_log  /var/log/nginx/error.log warn;
+pid        /run/nginx.pid;
+
+events { worker_connections  1024; }
+
+http {
+  include       /etc/nginx/mime.types;
+  default_type  application/octet-stream;
+  access_log    /var/log/nginx/access.log  main;
+  sendfile      on;
+
+  server {
+    listen 8080;
+    server_name _;
+
+    location / {
+      proxy_set_header Host $host;
+      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+      proxy_pass http://127.0.0.1:8080;
+    }
+  }
+}
+