fix(organize): stop keyword-dump tags from becoming folder names (#1119)

CivitAI tags are normally short single-concept labels, but some uploaders
pack their entire keyword list into one tag. The model in #1119 carries
"lora, character, rosie, irish, ... face" as a single 181-character tag.
Priority resolution matches aliases by exact equality, so that tag matched
nothing and resolve_priority_tag_for_model fell back to tags[0] -- the blob.
With the default "{base_model}/{first_tag}" template the model was filed
under "Krea 2/<181-character blob>/", and the full path plus the
".civitai.info" sidecar and the preview images next to it ran into the
Windows MAX_PATH limit.

Tags also bypassed sanitization on the way into a path: both
calculate_relative_path_for_model and DownloadManager._calculate_relative_path
sanitized model_name and version_name but interpolated {first_tag} verbatim,
so a tag containing "/" or ":" silently produced nested or illegal folders.

Two changes:

- The fallback skips tags that cannot serve as a folder name.
  is_usable_path_tag rejects comma-separated keyword dumps and tags longer
  than MAX_PATH_TAG_LENGTH; the resolver returns "" when nothing usable is
  left, which callers already render as "no tags". Whole-tag priority
  matching is untouched, so existing priority configurations behave the
  same.
- sanitize_folder_name gains an optional max_length, and every tag-derived
  segment now goes through it. Tags are capped at MAX_PATH_TAG_LENGTH, model
  and version names at MAX_FOLDER_NAME_LENGTH, and rendered filename stems at
  MAX_FILENAME_STEM_LENGTH.

For the reported model the folder becomes "Krea 2/base model" instead of the
blob, and the full path drops from 235 to 64 characters.

Existing libraries are not migrated up front: a path is only recomputed on
download, on an auto-organize run or when a filename template is applied, and
values already inside the caps are left byte-identical. Models previously
filed under a keyword-dump folder move on the next auto-organize run.

py/services/download_manager.py

@@ -25,6 +25,8 @@ from ..utils.models import (
 )
 from ..utils.constants import (
     CARD_PREVIEW_WIDTH,
+    MAX_FOLDER_NAME_LENGTH,
+    MAX_PATH_TAG_LENGTH,
     MODEL_WEIGHT_FILE_TYPES,
     SUPPORTED_DOWNLOAD_SKIP_BASE_MODELS,
     VALID_LORA_TYPES,
@@ -2327,16 +2329,26 @@ class DownloadManager:
         if not first_tag:
             first_tag = "no tags"  # Default if no tags available
 
+        # Tags come straight from CivitAI, so sanitize the value before it
+        # becomes a path segment and cap its length (#1119).
+        first_tag = sanitize_folder_name(first_tag, max_length=MAX_PATH_TAG_LENGTH)
+
         # Format the template with available data
         formatted_path = path_template
         formatted_path = formatted_path.replace("{base_model}", mapped_base_model)
         formatted_path = formatted_path.replace("{first_tag}", first_tag)
         formatted_path = formatted_path.replace("{author}", author)
         formatted_path = formatted_path.replace(
-            "{model_name}", sanitize_folder_name(model_info.get("name", ""))
+            "{model_name}",
+            sanitize_folder_name(
+                model_info.get("name", ""), max_length=MAX_FOLDER_NAME_LENGTH
+            ),
         )
         formatted_path = formatted_path.replace(
-            "{version_name}", sanitize_folder_name(version_info.get("name", ""))
+            "{version_name}",
+            sanitize_folder_name(
+                version_info.get("name", ""), max_length=MAX_FOLDER_NAME_LENGTH
+            ),
         )
 
         if model_type == "embedding":