fix(sidebar): keep the recipes storage dir out of folder management

The default recipes dir (<first lora root>/recipes) is auto-created by the
recipe scanner and recorded by the model-root walks as an empty folder, so
it showed up in the folder sidebar — and since recipe files are not model
weight files, the folder delete endpoint's model_count check let a
right-click delete wipe the whole recipe library via shutil.rmtree.

- scan walks (full scan, reconcile, all-folders backfill) no longer descend
  into the effective recipes dir, and get_all_folders() filters it out of
  snapshots persisted before the exclusion existed
- delete_folder/rename_folder refuse the recipes dir and any ancestor of
  it with code "protected"
- the delete modal renders a protected state (confirm hidden, per-row
  checkbox disabled) instead of a deletable 'no models' prediction
- RecipeScanner.recipes_dir now shares the side-effect-free resolver in
  py/utils/recipes_paths.py

locales/en.json

@@ -1416,6 +1416,8 @@
       "missingMessage": "This folder no longer exists on disk. Refresh the sidebar and try again.",
       "symlinkTitle": "Folder is a symbolic link",
       "symlinkMessage": "Every copy of this folder is a symbolic link; remove the link or its target outside LoRA Manager.",
+      "protectedTitle": "Folder is protected",
+      "protectedMessage": "This folder holds the recipe library and cannot be deleted from LoRA Manager.",
       "busyTitle": "A deletion is still pending",
       "checking": "Checking the folder contents...",
       "confirm": "Delete folder",
@@ -1458,6 +1460,7 @@
       "busyStatus": "a deletion is still pending",
       "missingStatus": "no longer exists on disk",
       "symlinkStatus": "symbolic link — cannot be deleted here",
+      "protectedStatus": "holds the recipe library — cannot be deleted here",
       "unknownStatus": "could not be checked",
       "deletedStatus": "deleted"
     },