feat: add configurable Bedrock inference profile support (#601)

## Summary

Add support for AWS Bedrock inference profiles configurable via
`BEDROCK_INFERENCE_PROFILE_ID` environment variable.

- Add `inference_profile_id` field to `BedrockEmbeddingConfig`
- Update `invoke_model` calls to use inference profile when configured
- Add comprehensive unit tests for inference profile functionality
- Maintain full backward compatibility when not configured

## Changes

### Core Implementation
- Added `inference_profile_id` field to `BedrockEmbeddingConfig` with
env var support
- Updated both sync and async `invoke_model` calls to conditionally
include `inferenceProfileId` parameter
- Enhanced TYPE_CHECKING client signatures for proper typing

### Testing
- Added unit tests for default behavior (None)
- Added unit tests for environment variable loading
- Added unit tests for manual configuration override
- All existing tests continue to pass

## Usage

Users can configure inference profiles in three ways:

```bash
# Environment variable (recommended)
export BEDROCK_INFERENCE_PROFILE_ID="arn:aws:bedrock:us-west-2:123456789012:inference-profile/my-profile"
```

```python
# Manual configuration
config = BedrockEmbeddingConfig(
    inference_profile_id="arn:aws:bedrock:us-west-2:123456789012:inference-profile/my-profile"
)
```

```python
# Default behavior (disabled)
config = BedrockEmbeddingConfig()  # inference_profile_id is None
```

## Test Plan

- [x] All existing Bedrock unit tests pass
- [x] New inference profile unit tests pass
- [x] Environment variable loading works correctly
- [x] Manual configuration override works
- [x] Backward compatibility maintained

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

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: tabossert