fix(cpp): highlight digit separators in defines

[iamdhrv]

Changes

• run the existing C/C++ number modes before string modes inside preprocessor directives
• add markup regressions for apostrophe digit separators in #define values
• add the required changelog entry

This prevents literals such as 100'000 in a macro definition from treating the apostrophe as the start of a string while preserving normal preprocessor string handling.

Resolves #4443

Validation

• npm run build
• ONLY_LANGUAGES="c cpp" npm run test-markup (18 passed)
• npm test (1578 passed, 3 pending)
• ESLint on the changed C and C++ grammar files
• git diff --check

Checklist

• Added markup tests for both affected languages
• Updated the changelog at CHANGES.md

Development note: implemented with Codex assistance and validated locally with the full Node.js test suite.

[github-actions]

Build Size Report

Changes to minified artifacts in /build, after gzip compression.

8 files changed

Total change +8 B

View Changes

file	base	pr	diff
es/core.min.js	8.24 KB	8.24 KB	-1 B
es/highlight.min.js	8.24 KB	8.24 KB	-1 B
es/languages/arduino.min.js	4.62 KB	4.62 KB	+1 B
es/languages/c.min.js	1.97 KB	1.97 KB	+2 B
es/languages/cpp.min.js	2.6 KB	2.6 KB	+2 B
languages/arduino.min.js	4.63 KB	4.63 KB	+2 B
languages/c.min.js	1.97 KB	1.98 KB	+2 B
languages/cpp.min.js	2.6 KB	2.6 KB	+1 B

[joshgoebel]

We either need more parsing examples or we'll need to lock this down to just #define if that's the intended scope - not all the other pre-processor directives.

[Baltsat]

I checked the exact head (854c6ed) with the full test and lint suite. The new NUMBERS entry applies to every PREPROCESSOR, so #if, #elif, and #line now highlight separator literals too, while the fixtures still cover only #define.

There is also a continued-definition case that currently breaks in both grammars:

#define LIMIT 10'\
000

This renders 10 as a number and the remainder as a string. After phase-2 line splicing, the logical token is 10'000, so it should remain one number token.

Could you add a regression for this form and make the numeric mode survive the continuation? Please also either add examples for the intended non-#define directives or confine the behavior to #define, as requested in the earlier scope review.