feat: trace direct raw summaries

[mag1cfrog]

Summary

• add direct raw trace events for measurement, range planning, packet write summaries, and sanitized failures
• emit DirectRawBulk debug summaries with row counts, column counts, encoded row counts, encoded byte counts, range counts, and elapsed time
• emit direct raw failure events with phase context, diagnostic codes, and sanitized error summaries
• cover direct raw summaries, packet write summaries, failure diagnostics, row-value redaction, and omitted raw packet count with unit fakes

Notes

The normal tiberius-raw-bulk write path does not expose raw packet counts. This PR intentionally emits safe range and byte summaries instead of guessing a raw_packet_count field.

Closes #146.

Validation

• cargo fmt --all --check
• cargo check --workspace
• cargo clippy --workspace --all-targets -- -D warnings
• cargo test --workspace
• git diff --check