feat: improve aircraft grouping — match by craft name from log header and/or filename

[nerdCopter]

Context

Aircraft grouping currently uses extract_aircraft_key() which strips the _YYYYMMDD_HHMMSS timestamp from the filename stem. For BLACKBOX_LOG-prefixed files (Betaflight/EmuFlight generic naming), the craft name from the post-date suffix is appended.

This works well when pilots use default firmware naming. It breaks or produces unexpected groups when:

• Pilots rename log files manually
• The craft name is absent from the filename
• Logs from different aircraft happen to share the same filename prefix

Proposal

Augment grouping to also consider the craft name embedded in the blackbox log header (the craft_name field present in Betaflight/EmuFlight blackbox headers). Using the header craft name as the primary grouping key — with filename stem as fallback — would make grouping robust regardless of how pilots name their files.

Considerations

• Header parsing already happens during log processing; the craft name field would need to be surfaced to the grouping logic before profiling begins.
• Pilots sometimes fly the same physical airframe under different craft names (e.g. after a firmware flash); this could inadvertently split what should be one group.
• Graceful fallback needed when the header craft name is absent or empty.

References

• Current implementation in extract_aircraft_key() — src/main.rs
• Discussed during feat: torque-inertia profiler & optimal P estimation (squash-rebase onto #143) #145 development; deferred as a separate improvement
• Related: perf/feat: eliminate double-parse and make optimal-P estimation default (no flag required) #146 (double-parse / make optimal-P default)