server-rpc/bark: Add some extra BlockHeight arithmetic guards

Duncan Deanrequested to merge
duncan/eng-513-audit-conversions-from-blockheight-and-use-appropriate into master

Summary by CodeRabbit

  • Bug Fixes
    • Improved confirmation and expiry calculations to avoid overflow/underflow in edge cases.
    • Added stricter validation for transaction and invoice expiry values, reducing the chance of accepting invalid data.
    • Hardened server-side handling of board confirmation settings so oversized values are rejected instead of misread.
Edited by coderabbit

Merge request reports