feat: add trace_metric_byte to DataCategory enum (#5626)

* feat: add trace_metric_byte to DataCategory enum

* chore: regenerate API dump with TraceMetricByte in DataCategory

* feat: record TraceMetricByte in client reports when trace metrics are discarded

Mirrors the LogByte pattern: records byte-level data category alongside the
item-level one when trace metrics are dropped by beforeSendMetrics, queue
overflow, or envelope discard.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* changelog: add trace_metric_byte data category entry

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: apply spotless formatting

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Roman Zavarnitsyn <rom4ek93@gmail.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>