7619aaefa9
Honour StreamOptions.headers in the Bedrock provider by attaching a Smithy build-step middleware that merges caller headers into the request before SigV4 signing. Reserved headers (x-amz-*, authorization, host) are silently skipped to preserve signing and the bearer-token auth path. No-op when no headers are supplied. Updates the StreamOptions.headers JSDoc to drop the Bedrock caveat.