Belge Şablonları now stores real files: POST /api/templates/upload
(multer -> Supabase Storage under templates/<user>/, then a templates
row), GET /api/templates/:id/download-url (short-lived signed URL),
and DELETE /api/templates/:id. Mounted at /api/templates.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
