feat: static sites feature with Gitea/GitHub/GitLab support and Deno backend

Deploy static content from Git repository folders with optional server-side
API endpoints. Supports Gitea/Forgejo/Gogs, GitHub, and GitLab with provider
autodetection.

- New Sites entity with CRUD, encrypted secrets, and manual/push/tag sync triggers
- Pluggable GitProvider interface with three implementations
- Deno container mode: auto-generates router from API_{method}_{name} exports
- Static container mode: nginx serving files with optional markdown rendering
- Wizard UI with provider selector, repo picker, branch/folder tree pickers
- Deploy pipeline builds fresh image, starts container, configures NPM proxy
- Stop/Start buttons, force redeploy on manual trigger
- Periodic health checker detects crashed containers
- Proxy route existence check during auto-sync

internal/proxy/none.go

@@ -17,6 +17,10 @@ func (n *NoneProvider) DeleteRoute(_ context.Context, _ string) error {
 	return nil
 }
 
+func (n *NoneProvider) RouteExists(_ context.Context, _ string) (bool, error) {
+	return true, nil
+}
+
 func (n *NoneProvider) ContainerLabels(_ string, _ int) map[string]string {
 	return nil
 }