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.

tests/services/test_settings_manager.py

@@ -365,6 +365,53 @@ def test_download_path_template_unknown_type_is_flat(manager):
     assert manager.get_download_path_template("not-a-model-type") == ""
 
 
+# Real CivitAI data for the model reported in issue #1119: the uploader dumped
+# a whole keyword list into a single tag.
+KEYWORD_DUMP_TAG = (
+    "lora, character, rosie, irish, redhead, auburn, freckles, green eyes, "
+    "curly hair, woman, female, photorealistic, realistic, krea2, dark beast, "
+    "kreativity, nsfw, nude, portrait, face"
+)
+
+
+def test_resolve_priority_tag_prefers_configured_priority(manager):
+    # Priority order from CIVITAI_MODEL_TAGS: "character" precedes "anime".
+    assert manager.resolve_priority_tag_for_model(["anime", "character"], "lora") == (
+        "character"
+    )
+
+
+def test_resolve_priority_tag_falls_back_to_first_usable_tag(manager):
+    assert (
+        manager.resolve_priority_tag_for_model(["portrait", "anime-ish"], "lora")
+        == "portrait"
+    )
+
+
+def test_resolve_priority_tag_skips_keyword_dump_tag(manager):
+    """A keyword-dump tag must not be used as a folder name (#1119)."""
+    assert manager.resolve_priority_tag_for_model([KEYWORD_DUMP_TAG], "lora") == ""
+
+
+def test_resolve_priority_tag_skips_keyword_dump_and_uses_next_tag(manager):
+    assert (
+        manager.resolve_priority_tag_for_model([KEYWORD_DUMP_TAG, "portrait"], "lora")
+        == "portrait"
+    )
+
+
+def test_resolve_priority_tag_skips_unusable_tags(manager):
+    overlong_tag = "x" * 51
+
+    assert manager.resolve_priority_tag_for_model([overlong_tag], "lora") == ""
+    assert manager.resolve_priority_tag_for_model([overlong_tag, "  "], "lora") == ""
+    # Non-string entries never win the fallback.
+    assert manager.resolve_priority_tag_for_model([None, 42], "lora") == ""
+    # A tag at the length budget is still accepted and stripped.
+    assert manager.resolve_priority_tag_for_model(["x" * 50], "lora") == "x" * 50
+    assert manager.resolve_priority_tag_for_model(["  portrait  "], "lora") == "portrait"
+
+
 def test_auto_set_default_roots(manager):
     # Clear any previously auto-set values to test fresh behavior
     manager.settings["default_lora_root"] = ""