fix: setup_ops_repo should create ops repo under disinto-admin, not the authenticated bot (#240)

- Replace POST /api/v1/users/{owner}/repos fallback with admin API
  POST /api/v1/admin/users/{org_name}/repos, which creates in the target
  namespace regardless of which user is authenticated
- Fix ops_slug derivation in disinto_init to always use disinto-admin
  as owner instead of deriving from forge_repo (which may be johba/...)
- Update projects/disinto.toml.example ops_repo default to disinto-admin/disinto-ops

projects/disinto.toml.example

@@ -5,7 +5,7 @@
 
 name            = "disinto"
 repo            = "johba/disinto"
-ops_repo        = "johba/disinto-ops"
+ops_repo        = "disinto-admin/disinto-ops"
 forge_url       = "http://localhost:3000"
 repo_root       = "/home/YOU/dark-factory"
 ops_repo_root   = "/home/YOU/disinto-ops"