feat: add Hugging Face as a first-class inference provider (#3419)

Salvage of PR #1747 (original PR #1171 by @davanstrien) onto current main.

Registers Hugging Face Inference Providers (router.huggingface.co/v1) as a named provider:
- hermes chat --provider huggingface (or --provider hf)
- 18 curated open models via hermes model picker
- HF_TOKEN in ~/.hermes/.env
- OpenAI-compatible endpoint with automatic failover (Groq, Together, SambaNova, etc.)

Files: auth.py, models.py, main.py, setup.py, config.py, model_metadata.py, .env.example, 5 docs pages, 17 new tests.

Co-authored-by: Daniel van Strien <davanstrien@gmail.com>

hermes_cli/auth.py

@@ -212,6 +212,14 @@ PROVIDER_REGISTRY: Dict[str, ProviderConfig] = {
         api_key_env_vars=("KILOCODE_API_KEY",),
         base_url_env_var="KILOCODE_BASE_URL",
     ),
+    "huggingface": ProviderConfig(
+        id="huggingface",
+        name="Hugging Face",
+        auth_type="api_key",
+        inference_base_url="https://router.huggingface.co/v1",
+        api_key_env_vars=("HF_TOKEN",),
+        base_url_env_var="HF_BASE_URL",
+    ),
 }
 
 
@@ -685,6 +693,7 @@ def resolve_provider(
         "github-copilot-acp": "copilot-acp", "copilot-acp-agent": "copilot-acp",
         "aigateway": "ai-gateway", "vercel": "ai-gateway", "vercel-ai-gateway": "ai-gateway",
         "opencode": "opencode-zen", "zen": "opencode-zen",
+        "hf": "huggingface", "hugging-face": "huggingface", "huggingface-hub": "huggingface",
         "go": "opencode-go", "opencode-go-sub": "opencode-go",
         "kilo": "kilocode", "kilo-code": "kilocode", "kilo-gateway": "kilocode",
     }