fs: coerce FileHandle.read length like fs.read

[bun-unsafe]

Summary

fs.promises.FileHandle.read() forwarded a non-number length (for example "5") into binding.read. node::fs::Read requires args[3]->IsInt32() and aborts the process on a debug/CHECK failure.

fs.read / fs.readSync already coerce with length |= 0 after defaulting. This applies the same step on the promises path so a bad length cannot reach C++.

Test plan

• ./node test/parallel/test-fs-promises-file-handle-read.js
• Existing FileHandle.read cases (empty length, options object, null/undefined length) still pass on CI

const fh = await fs.promises.open(file, 'r');
await fh.read(Buffer.alloc(20), 0, '5', 0); // must not abort; bytesRead === 5

[github-actions]

Failed to start CI

- Validating Jenkins credentials
✔  Jenkins credentials valid
- Starting PR CI job
✘  Failed to start PR CI: 400 Bad Request

https://github.com/nodejs/node/actions/runs/32773413890

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.15%. Comparing base (f509cf1) to head (dcefcbc).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #65521   +/-   ##
=======================================
  Coverage   90.14%   90.15%           
=======================================
  Files         751      751           
  Lines      253585   253586    +1     
  Branches    47772    47773    +1     
=======================================
+ Hits       228596   228620   +24     
+ Misses      16228    16204   -24     
- Partials     8761     8762    +1     

Files with missing lines	Coverage Δ
lib/internal/fs/promises.js	92.65% <100.00%> (+<0.01%)	⬆️

... and 28 files with indirect coverage changes

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