fix: escape generated CSS selectors

[yearth]

Summary

• escape CSS-special class and ID tokens in selectors emitted by --outline and --locate
• preserve the existing tag.class / tag#id output shape without adding a dependency
• verify emitted selectors round-trip back into ax extraction

Motivation

Tailwind-style classes such as sm:w-1/2 currently produce selectors like div.sm:w-1/2, which fail when passed back to ax because : is parsed as a pseudo-class.

Tests

• bun test (81 pass)
• bun run format
• bun run build

[yusukebe]

LGTM!

[yusukebe]

@yearth Thanks again!