fix(CodeWindow): don't treat // inside a string as a comment

[chinesepowered]

What

CodeWindow's syntax highlighter finds a trailing line comment with:

const ci = line.indexOf('//');

That also matches // inside a string literal. So a perfectly normal line like:

const url = 'https://example.com'

gets split at the // inside the string — everything from //example.com' onward (including the closing quote) is rendered as a grey cw-com comment, and the string is no longer highlighted correctly.

Fix

Scan the line for the first // that occurs outside any string literal (single, double, or backtick, with escape handling), via a small commentStart helper, and use that index instead of indexOf('//').

Lines with no code-level comment, and comments that genuinely trail code, are unaffected.

Changes

• src/components/CodeWindow.tsx — add commentStart(line); use it in hl() in place of line.indexOf('//').

Verification

• npx tsc --noEmit ✓
• npm run build ✓