`.map-tool` leaves the map's stylesheet: no control renders it #5251

Intent: cut the fat: no stylesheet rule that no page needs. .map-tool is styled in src/web/pages/map.ts (near lines 1124-1126) but no markup or client script writes it.

Done:

• [ ] a search of src/ (map.ts's markup and its client script, client.ts) shows nothing writes map-tool; the map page looks the same at 390px and 1280px (screenshots)
• [ ] the rules leave src/web/pages/map.ts, and each class's line leaves docs/DESIGN.md §5d
• [ ] bun scripts/design-lint.ts passes, and the tests for the pages named pass
• [ ] a test asserts the stylesheet no longer contains the class names

Files: src/web/pages/map.ts, docs/DESIGN.md (only the retired lines).