lib: fix validatePort to reject string '0' when allowZero is false

[deepview-autofix]

The port === 0 && !allowZero check used strict equality, so the string '0' (and other numeric-zero string forms like '0x0') slipped through because '0' === 0 is false. As a result, validatePort('0', name, false) returned 0, contradicting the allowZero=false contract and letting callers such as dgram.Socket#connect('0', ...) proceed past the validator and fail deep in the stack with EADDRNOTAVAIL while leaking the handle.

Compare the numeric coercion (+port === 0) so all numeric-zero forms are rejected consistently.

[ChALkeR]

This is mine (code scanner + autofix)

I also validated the issue in dgram Socket.prototype.connect

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.62%. Comparing base (14e16db) to head (3796b48).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62836      +/-   ##
==========================================
- Coverage   89.62%   89.62%   -0.01%     
==========================================
  Files         706      706              
  Lines      219136   219136              
  Branches    41987    41984       -3     
==========================================
- Hits       196404   196395       -9     
- Misses      14611    14619       +8     
- Partials     8121     8122       +1     

Files with missing lines	Coverage Δ
lib/internal/validators.js	98.25% <100.00%> (ø)

... and 36 files with indirect coverage changes

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