feat(settings): pick a local model from a dropdown of existing .cmf files

- New GET /admin/api/cmf/files lists the .cmf files (and tensor-dir .cmf) under
  models_dir, with sizes.
- Settings → Local models: the per-row model field is now a dropdown of those
  files instead of a hand-typed path, and auto-fills the id from the filename.

web/js/i18n/en.js

@@ -244,9 +244,10 @@ export default {
   "settings.cmf.threads": "Worker threads",
   "settings.cmf.gpu": "Use GPU (Metal / wgpu)",
   "settings.cmf.speedNote": "Threads parallelise the decode matvecs (~3x faster; 0 = runtime default). GPU offload mainly helps prefill of long prompts — decode is memory-bandwidth-bound, so on Apple Silicon it is roughly neutral.",
+  "settings.cmf.pick": "select a model",
   "settings.cmf.models": "Local models",
   "settings.cmf.modelsHelp": "Each row is one model the gateway runs (its own cortiq serve on its own port) and registers in the pool. Add as many as you have .cmf files and free ports.",
-  "settings.cmf.rowHint": "id · path to .cmf · port · threads · GPU. Changes apply on restart; deleting a row stops that server.",
+  "settings.cmf.rowHint": "id · .cmf file · port · threads · GPU. Changes apply on restart; deleting a row stops that server.",
   "settings.cmf.addServer": "+ Add local model",
   "settings.cmf.checkPort": "Check port",
   "settings.cmf.portFree": "port is free",