Add Hugging Face support and enhance model resolution logic

- Introduced support for Hugging Face API integration, allowing fallback model resolution when Civitai fails.
- Updated configuration to include `HF_TOKEN` and `HF_TOKEN_PATH` for authentication.
- Enhanced model capture logic to differentiate between Civitai and Hugging Face sources.
- Improved error handling for model downloads, providing clearer messages for authentication issues.
- Updated documentation to reflect new environment variables and usage instructions for Hugging Face integration.
- Added tests to validate the new fallback mechanism and ensure robust model resolution.

src/gpu_rent/config.py

@@ -83,6 +83,7 @@ class Config:
 
     civitai_api_token: str
     civitai_api_host: str
+    hf_token: str
     models_manifest: Path
     extensions_manifest: Path
     git_token: str
@@ -215,6 +216,9 @@ def load_config(*, require_auth: bool = True) -> Config:
         boot_snapshot_name=(os.environ.get("BOOT_SNAPSHOT_NAME") or "gpu-rent-boot-ok").strip(),
         civitai_api_token=(os.environ.get("CIVITAI_API_TOKEN") or "").strip(),
         civitai_api_host=(os.environ.get("CIVITAI_API_HOST") or "civitai.red").strip().lower(),
+        hf_token=(
+            os.environ.get("HF_TOKEN") or os.environ.get("HUGGING_FACE_HUB_TOKEN") or ""
+        ).strip(),
         models_manifest=models_manifest,
         extensions_manifest=extensions_manifest,
         git_token=(os.environ.get("GIT_TOKEN") or "").strip(),