Strengthen profiling compatibility validation and kernel attribution

[lullu57]

Summary

Counter-set preflight validation currently checks only whether metric names appear in ncu --query-metrics. It does not validate actual support on the target kernel/device/replay path, and kernel-row attribution during profiling is fragile when no kernel regex is configured.

Evidence

• src/kernel_tuner/profiling/compatibility.py:47
• src/kernel_tuner/profiling/compatibility.py:59
• src/kernel_tuner/profiling/adapter.py:65
• src/kernel_tuner/profiling/adapter.py:124
• src/kernel_tuner/profiling/adapter.py:276
• docs/research/04_signal_and_profiling_plan.md:100

Why This Matters

The system can mark a counter set acceptable for reportable use even when the counters are not reliably obtainable for the actual profiled kernel. It can also attribute counters to the wrong kernel row.

Expected Fix

• Strengthen compatibility validation beyond simple metric-name discovery.
• Improve kernel-row attribution, ideally with explicit kernel filtering for reportable counter sets.
• Document fallback behavior when exact attribution is not possible.

Acceptance Criteria

• Reportable counter sets use defensible kernel attribution.
• Preflight acceptance is harder to produce as a false positive.
• Tests cover compatibility and row-selection behavior.