Tracks a running total of ingested log bytes (approximated as each log's raw UTF-8 text length), incremented on ingest and decremented in evict_excess_logs when a log is dropped. Exposed via StatsDto's new approx_bytes_total field on GET /api/stats, and displayed in NavMenu's stats panel formatted with toLocaleString() (comma separators). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01XFUNZwCvz3kcod3352ZR2o