* feat(bedrock): add structured output support via Converse API (Fixes#5966)
* fix(bedrock): improve unsupported model exception handling and schema parsing
* refactor(bedrock): use generic traversal for strict schema enforcement
* address Copilot review comments on structured output
* refine bedrock structured output: guard additionalProperties, TypeError check, docs + test
* fix(bedrock): widen response_format to Mapping and add missing test coverage