fix(isFloat): reject bare-exponent strings like "e5"

[nikolauspschuetz]

Bug

isFloat returns true for strings that are only an exponent, with no mantissa:

isFloat('e5')   // true  ❌  (parseFloat('e5') === NaN)
isFloat('E5')   // true  ❌
isFloat('.e3')  // true  ❌
isFloat('e-3')  // true  ❌
isFloat('+e5')  // true  ❌

The validation regex makes every segment optional — sign, integer part, fraction, and exponent — so a string consisting of just an exponent matches. The function never rejects the NaN that its own parseFloat produces.

The bug only surfaces on the common no-min/max call: when a bound is supplied, NaN >= min is false and the string is (incidentally) rejected.

Fix

Guard the result with !Number.isNaN(value).

value was computed as parseFloat(str.replace(',', '.')) — only the comma separator was normalized. To keep the NaN check correct for locales whose decimal separator is neither . nor , (e.g. ar-JO, which uses ٫), value is now computed with the locale-aware separator. This is a no-op for the default/en/de-DE locales and makes the guard sound across all locales.

Test

Added 'e5', 'E5', '.e3', 'e-3', '+e5' to the invalid list of the default isFloat test.

Verified fails-before / passes-after: with the src change reverted the should validate floats suite fails on the new cases; with the fix the full suite (default, en-AU, de-DE, ar-JO, and the min/max/lt/gt blocks) passes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (b18bde8) to head (0e2554a).

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #2831   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files          114       114           
  Lines         2600      2601    +1     
  Branches       659       659           
=========================================
+ Hits          2600      2601    +1     

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