feat: add OpenAI-compatible Bedrock provider with error handling

Implements AWS Bedrock inference provider using OpenAI-compatible endpoint
for Llama models available through Bedrock.

Changes:
- Add BedrockInferenceAdapter using OpenAIMixin base
- Configure region-specific endpoint URLs
- Add NotImplementedError stubs for unsupported endpoints
- Implement authentication error handling with helpful messages
- Remove unused models.py file
- Add comprehensive unit tests (12 total)
- Add provider registry configuration

tests/unit/providers/inference/test_bedrock_adapter.py

@@ -0,0 +1,81 @@
+# 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 types import SimpleNamespace
+from unittest.mock import AsyncMock, MagicMock
+
+import pytest
+from openai import AuthenticationError
+
+from llama_stack.apis.inference import OpenAIChatCompletionRequestWithExtraBody
+from llama_stack.providers.remote.inference.bedrock.bedrock import BedrockInferenceAdapter
+from llama_stack.providers.remote.inference.bedrock.config import BedrockConfig
+
+
+def test_adapter_initialization():
+    config = BedrockConfig(api_key="test-key", region_name="us-east-1")
+    adapter = BedrockInferenceAdapter(config=config)
+
+    assert adapter.config.api_key == "test-key"
+    assert adapter.config.region_name == "us-east-1"
+
+
+def test_client_url_construction():
+    config = BedrockConfig(api_key="test-key", region_name="us-west-2")
+    adapter = BedrockInferenceAdapter(config=config)
+
+    assert adapter.get_base_url() == "https://bedrock-runtime.us-west-2.amazonaws.com/openai/v1"
+    assert adapter.get_api_key() == "test-key"
+
+
+def test_api_key_from_config():
+    """Test API key is read from config"""
+    config = BedrockConfig(api_key="config-key", region_name="us-east-1")
+    adapter = BedrockInferenceAdapter(config=config)
+
+    assert adapter.get_api_key() == "config-key"
+
+
+def test_api_key_from_header_overrides_config():
+    """Test API key from request header overrides config via client property"""
+    config = BedrockConfig(api_key="config-key", region_name="us-east-1")
+    adapter = BedrockInferenceAdapter(config=config)
+    adapter.provider_data_api_key_field = "aws_bedrock_api_key"
+    adapter.get_request_provider_data = MagicMock(return_value=SimpleNamespace(aws_bedrock_api_key="header-key"))
+
+    # The client property is where header override happens (in OpenAIMixin)
+    assert adapter.client.api_key == "header-key"
+
+
+async def test_authentication_error_handling():
+    """Test that AuthenticationError from OpenAI client is converted to ValueError with helpful message"""
+    config = BedrockConfig(api_key="invalid-key", region_name="us-east-1")
+    adapter = BedrockInferenceAdapter(config=config)
+
+    # Mock the parent class method to raise AuthenticationError
+    mock_response = MagicMock()
+    mock_response.message = "Invalid authentication credentials"
+    auth_error = AuthenticationError(message="Invalid authentication credentials", response=mock_response, body=None)
+
+    # Create a mock that raises the error
+    mock_super = AsyncMock(side_effect=auth_error)
+
+    # Patch the parent class method
+    original_method = BedrockInferenceAdapter.__bases__[0].openai_chat_completion
+    BedrockInferenceAdapter.__bases__[0].openai_chat_completion = mock_super
+
+    try:
+        with pytest.raises(ValueError) as exc_info:
+            params = OpenAIChatCompletionRequestWithExtraBody(
+                model="test-model", messages=[{"role": "user", "content": "test"}]
+            )
+            await adapter.openai_chat_completion(params=params)
+
+        assert "AWS Bedrock authentication failed" in str(exc_info.value)
+        assert "Please check your API key" in str(exc_info.value)
+    finally:
+        # Restore original method
+        BedrockInferenceAdapter.__bases__[0].openai_chat_completion = original_method