- Added APIs to store, retrieve, and clone upstream response headers in context for detailed logging.
- Updated `RecordAPIResponseMetadata`, `RecordAPIWebsocketHandshake`, and related methods to capture response headers.
- Extended `UsageReporter` to include response headers in published usage records.
- Enhanced payload tests to validate response headers' integrity and persistence.
- Refactored `usage.Record` to support optional `ResponseHeaders` field.
- Introduced reusable utilities in `requestmeta` to manage endpoint and response status in request contexts.
- Refactored plugins and handlers to use context-based metadata, removing direct dependency on `gin`.
- Updated tests to validate new context utilities and replaced `gin`-based context handling.
Fixed: #3166