refactor: implement _summary_list_field function to streamline handling of summary fields in coach summary; enhance payload processing and validation for string and list types

refactor: add functions for JSON payload extraction and validation in coach summary; streamline summary key handling and improve error reporting

refactor: introduce compact representation functions for metrics, issues, and knowledge cards; enhance summary evidence generation and improve error handling in JSON extraction

refactor: enhance JSON response handling in coach summary generation; update response format instructions and improve error reporting for invalid JSON outputs

Implement grounded coach summary with HF SLM

Implement frame-level issue markers

refactor(ui): clarify mocked downstream analysis

first commit