fix(devnet): confirm transient one-block soak skew

[gkalombo21]

Summary

Confirms transient one-block height skew before classifying a soak sample as temporarily skewed.

Changes

• Adds a confirmation height reread when:
  • all nodes are reachable
  • tips are consistent
  • raw height spread equals 1
• Keeps the raw heightSpread value in samples.csv
• Uses the confirmed spread only for convergence classification
• Adds focused PowerShell tests

Validation

• PowerShell parse: PASS
• Tests: 15/15 PASS
• 2-hour smoke soak: PASS WITH WARNINGS
• 121 samples over 121 minutes
• Producer progressed by 1,446 blocks
• Converged: 100%
• RPC availability: 100%
• REST availability: 100%
• Restarts: 0
• No protocol or consensus changes

Notes

• One non-fatal producer log error was counted during the first interval.
• The PID recognition issue observed in stop-soak.ps1 is unrelated and should be handled separately.