feat: add routes page with route builder and saved routes

[ktnielse]

Summary

Adds the routes page (#/ruter), reusing the map and side panel from the explore page.

• My routes: lists saved routes. Opening one shows it on the map and lists its stops in the panel. Selecting a stop shows the place details, and the back arrow returns to the route.
• Create route: add stops by searching or clicking a pin, then save the route with a name (max 30 characters). It appears under "My routes".

Notes

• Routes are stored in localStorage behind api/routes.ts, to be replaced by GraphQL calls later.
• MapViewport got optional props for the route line, numbered pins and fit-to-places.
• Extracted usePanelInset and matchesQuery so both map pages share them.
• Added tests for the routes api and page.

Issues

Related to #17 and #18.

[andss]

Reviewed the routes page, route builder, local storage API, shared map changes and tests.

The implementation reuses the existing map and place-detail components well. Route creation supports adding and removing stops, requires at least two stops before saving, and limits the route name to 30 characters. Saved routes preserve the stop order and can be reopened to view the route and individual place details.

The draft-stop interaction is now fixed: clicking a stop opens its details, and “Back to draft” returns to the existing draft. The new regression test covers this flow. The tests also cover saving routes, persistence after reload and invalid stored data.

Using localStorage is clearly documented as a temporary solution until GraphQL integration is ready.

All 16 tests, the production build, formatting and lint checks pass. No blocking issues found. Approved.