feat: add api.llama provider, llama-guard-4 model (#2058)

This PR adds a llama-stack inference provider for `api.llama.com`, as
well as adds entries for Llama-Guard-4 and updated Prompt-Guard models.

llama_stack/providers/remote/inference/llama_openai_compat/config.py

@@ -0,0 +1,38 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+from typing import Any, Dict, Optional
+
+from pydantic import BaseModel, Field
+
+from llama_stack.schema_utils import json_schema_type
+
+
+class LlamaProviderDataValidator(BaseModel):
+    llama_api_key: Optional[str] = Field(
+        default=None,
+        description="API key for api.llama models",
+    )
+
+
+@json_schema_type
+class LlamaCompatConfig(BaseModel):
+    api_key: Optional[str] = Field(
+        default=None,
+        description="The Llama API key",
+    )
+
+    openai_compat_api_base: str = Field(
+        default="https://api.llama.com/compat/v1/",
+        description="The URL for the Llama API server",
+    )
+
+    @classmethod
+    def sample_run_config(cls, api_key: str = "${env.LLAMA_API_KEY}", **kwargs) -> Dict[str, Any]:
+        return {
+            "openai_compat_api_base": "https://api.llama.com/compat/v1/",
+            "api_key": api_key,
+        }