feat: add Applications admin page with version upload and deployments

- SplitPane layout with environment selector, app list, and detail pane
- Create/delete apps with slug uniqueness validation
- Upload JAR versions with file size display
- Deploy versions and stop running deployments with status badges
- Deployment list auto-refreshes every 5s for live status updates
- Registered at /admin/apps with sidebar entry

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/components/sidebar-utils.ts

@@ -94,11 +94,12 @@ export function buildAppTreeNodes(
 }
 
 /**
- * Admin tree — static 6 nodes.
+ * Admin tree — static nodes.
  */
 export function buildAdminTreeNodes(): SidebarTreeNode[] {
   return [
     { id: 'admin:environments', label: 'Environments', path: '/admin/environments' },
+    { id: 'admin:apps', label: 'Applications', path: '/admin/apps' },
     { id: 'admin:rbac', label: 'Users & Roles', path: '/admin/rbac' },
     { id: 'admin:audit', label: 'Audit Log', path: '/admin/audit' },
     { id: 'admin:oidc', label: 'OIDC', path: '/admin/oidc' },