feat: Projekt-Typ Vorlage (template) - login-geschuetzt, isTemplate-Flag

- neuer Typ template: hasWebsite wie preview, isPublic=false, isTemplate=true
- deriveProjectType erkennt isTemplate; Appwrite-Update schreibt isTemplate
- .webklar-preview.json bekommt template-Flag

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/services/giteaAdmin.js

@@ -316,9 +316,11 @@ export async function createProjectFromTemplate({
  * kein expliziter Typ mitgegeben wurde.
  *   preview  -> Website mit Login-geschuetzter Preview (Standard)
  *   website  -> oeffentliche Website ohne Login
+ *   template -> Website-Vorlage (login-geschuetzt, nur Admin, in Vorlagen-Ansicht)
  *   project  -> internes Projekt ohne Hosting/Subdomain
  */
 function deriveProjectType(doc) {
+  if (doc?.isTemplate) return 'template'
   if (doc?.isPublic) return 'website'
   if (doc?.subdomain) return 'preview'
   return 'project'
@@ -354,8 +356,11 @@ export async function updateWebsiteProject(projectId, { projectName, subdomain,
 
   const nextName = String(projectName ?? doc.projectName ?? '').trim() || doc.projectName || repoSlug || ''
   const nextType = projectType || deriveProjectType(doc)
-  const hasWebsite = nextType === 'preview' || nextType === 'website'
+  // template = login-geschuetzte Vorlage: braucht Preview (wie 'preview'), aber
+  // nicht oeffentlich; wird als isTemplate markiert.
+  const hasWebsite = nextType === 'preview' || nextType === 'website' || nextType === 'template'
   const isPublic = nextType === 'website'
+  const isTemplate = nextType === 'template'
 
   const oldSubdomain = doc.subdomain || ''
   let nextSubdomain = ''
@@ -394,6 +399,7 @@ export async function updateWebsiteProject(projectId, { projectName, subdomain,
     templateName: doc.templateName || config.gitea.templateRepo,
     projectType: nextType,
     public: isPublic,
+    template: isTemplate,
     ...(hasWebsite && nextSubdomain ? { subdomain: nextSubdomain } : {}),
   }
 
@@ -437,6 +443,7 @@ export async function updateWebsiteProject(projectId, { projectName, subdomain,
     previewUrl,
     projectType: nextType,
     isPublic,
+    isTemplate,
     status: hasWebsite ? (deployResult.deployed ? 'deployed' : 'pending') : 'created',
     provisioningStatus: hasWebsite
       ? (deployResult.deployed ? 'ready' : (deployResult.error ? 'deploy_failed' : 'pending'))