A repository's two-column layout uses base.ts grid utilities, and .repo-layout leaves the stylesheet #4592

Done:

• [ ] src/web/pages/repo.ts lays the two columns with base.ts grid utilities
• [ ] .repo-layout's rules leave src/web/style/content.ts and docs/DESIGN.md §5d
• [ ] a test asserts no repo-layout, and a look shows no layout shift at 375 px and 1280 px

Run bun scripts/design-lint.ts and bun test test/design-lint.test.ts before pushing; where counts fall, lower docs/design/baseline.json in the same pull. Replaces #3944: the crew's two tries went red on tests this change does not touch (those are planned separately), so keep the diff to the files named.