Enable remote compaction for Amazon Bedrock (#36981)

## What changed

- Add provider-owned remote compaction capabilities for unsupported, v1, and v2 protocols.
- Mark Amazon Bedrock as v1-only so manual and automatic compaction use `/v1/responses/compact`, even when the v2 feature is enabled.
- Preserve v2 support for OpenAI and Azure Responses providers and local compaction for unsupported providers.

## Testing

- Cover Amazon Bedrock manual and automatic remote compaction, including endpoint selection, authentication headers, model selection, and reuse of the compacted summary.

GitOrigin-RevId: d58093178605d1f8155b93d9a161408177f6ac72

codex-rs/model-provider/src/lib.rs

@@ -22,5 +22,6 @@ pub use provider::ProviderAccountError;
 pub use provider::ProviderAccountResult;
 pub use provider::ProviderAccountState;
 pub use provider::ProviderCapabilities;
+pub use provider::RemoteCompactionSupport;
 pub use provider::SharedModelProvider;
 pub use provider::create_model_provider;