Fix regex character class parsing

[davejcameron]

Problem

Regex literals can contain / inside character classes, but the parser currently treats the first / as the end of the regex body even when it appears inside [...].

Fix

Track when the regex scanner is inside a character class, so / only terminates the literal outside of character classes. Escapes continue to consume the escaped character as part of the pattern.

Add focused regex coverage for character classes containing /.

Validation

• Added regex parser coverage for / inside character classes

[dy]

Landed on main in eac665c.

The branch was CONFLICTING — its base predates current main and carried an unrelated /= (c === 61) guard that belongs to a separate PR and would break the existing /=/g test. So the character-class fix alone was applied directly:

let cls = false;
const pattern = next(c =>
  c === BSLASH ? 2 :
  c === LBRACK ? (cls = true, 1) :
  c === RBRACK ? (cls = false, 1) :
  c && (cls || c !== SLASH)
);

Added test('regex: character classes', ...) covering /[^/]+$/, /[\]/]/, and a .match eval case. Full suite green (336 pass, 0 fail). Closing as resolved.