Load codex_client_models.json like models.json with validation, revisioned
handler reloads, CI bake, and Home-aware updater gates so list IDs still
come from Home while templates can refresh on the edge.
Start the normal server when template api-keys are detected, but keep proxy API endpoints disabled until the keys are updated.
Show the warning page on / and /management.html, add a button to open the management panel via /management.html?safe-mode=configure, and remove the old warning-only server path.
Fixes#4063
