fix: allow .index.json files for sharded model linking

Updated find_model_files() to include .index.json files in the file
discovery logic. These files are essential for sharded models like
CogVideoX which split safetensors into multiple parts.

Changes:
- Modified JSON file filtering to allow files ending with .index.json
- Updated comment to document support for sharded model index files

Fixes automatic linking for:
- CogVideoX-5b (3 files including index.json)
- CogVideoX-5b-I2V (4 files including index.json)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

artifact_huggingface_download.sh

@@ -428,11 +428,11 @@ for file_path in latest_snapshot.rglob('*'):
         if filename_filter and filename_filter not in file_path.name:
             continue
         # Skip metadata files except important config files
-        # Allow: config.json, tokenizer.json, tokenizer_config.json, sentencepiece models
+        # Allow: config.json, tokenizer.json, tokenizer_config.json, sentencepiece models, .index.json for sharded models
         important_files = ('config.json', 'tokenizer.json', 'tokenizer_config.json', '.model')
         if file_path.name.endswith(('.txt', '.md', '.gitattributes')):
             continue
-        if file_path.name.endswith('.json') and not file_path.name in important_files:
+        if file_path.name.endswith('.json') and not (file_path.name in important_files or file_path.name.endswith('.index.json')):
             continue
         print(str(file_path))
         file_count += 1