Discovered config files that failed to parse or validate, (path, error).
Surfaced even on success: a broken project .mcp.json (or an approved
server that fails per-server validation) can be dropped while another
discovered config still loads. Reporting it here matches
resolve_and_load_mcp_tools, which emits the same failures as
status="error" rows rather than swallowing them. On ConfigResolutionError
the reason is already embedded in message, so the field lives only here.
See format_load_errors_notice.
