feat(settings): filename templates for download and bulk rename (#1071)

Add per-model-type filename templates ({model_name}, {version_name},
{base_model}, {author}, {first_tag}, {hash_short}, {original_name}) so
downloaded files get informative names instead of e.g. V1.safetensors.
Empty template keeps the current filename (opt-in, off by default).

- apply template automatically after downloads; rename conflicts keep
  the original name and never fail the download
- record original_file_name in metadata on rename for traceability
- bulk apply via GET|POST /api/lm/{prefix}/apply-filename-template with
  WebSocket progress, sharing the auto-organize lock
- settings UI lives in the new Organization tab with validation, live
  preview, and per-type 'apply to library' actions

py/services/use_cases/__init__.py

@@ -20,6 +20,7 @@ from .example_images import (
     ImportExampleImagesUseCase,
     ImportExampleImagesValidationError,
 )
+from .filename_template_use_case import FilenameTemplateUseCase
 
 __all__ = [
     "AutoOrganizeInProgressError",
@@ -34,4 +35,5 @@ __all__ = [
     "DownloadExampleImagesUseCase",
     "ImportExampleImagesUseCase",
     "ImportExampleImagesValidationError",
+    "FilenameTemplateUseCase",
 ]