Fix signed comparison in ElectrumClient

[tnull]

GetHistoryRes::height from electrum-client is a signed integer. Here we first check for <= 0 before casting to u32.

[ldk-reviews-bot]

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[ldk-claude-review-bot]

I've reviewed the full diff and examined all related height as u32 casts in the file. The fix is correct:

• Before: history.height (a signed i32) was cast to u32 before the <= 0 check, so negative values (e.g., -1 for unconfirmed-with-unconfirmed-inputs) would wrap to large positive numbers, bypassing the guard entirely.
• After: The comparison happens on the signed value, and the as u32 cast only occurs when height > 0.

The other height as u32 casts in the file (lines 97, 253) operate on HeaderNotification::height which is usize (unsigned), so they don't have the same issue. The cast at line 380 is already guarded by the pre-existing check at line 354.

No issues found.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.23%. Comparing base (2313bd5) to head (8b383bb).
⚠️ Report is 35 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4590      +/-   ##
==========================================
- Coverage   87.08%   86.23%   -0.86%     
==========================================
  Files         161      159       -2     
  Lines      109255   109103     -152     
  Branches   109255   109103     -152     
==========================================
- Hits        95147    94083    -1064     
- Misses      11627    12410     +783     
- Partials     2481     2610     +129     

Flag	Coverage Δ
fuzzing-fake-hashes	?
fuzzing-real-hashes	?
tests	86.23% <ø> (+0.06%)	⬆️

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