Declutter the map at low zoom with station dots

[rodrigohpalmeirim]

Makes the map legible when zoomed out: instead of always drawing every station as a full pin, stations degrade gracefully with zoom, and the stations that matter for the current route stay prominent. Fixes the route-overview problem where fitting a computed route zoomed out and buried the route line under 150+ pins.

Dots at low zoom (station-dots layer)

• Below zoom 14 stations are drawn as small dots instead of pins — the bike count baked into the pin sprite is unreadable at those sizes anyway, so the pins were pure clutter
• Dot color carries the station's state, matching the pin semantics: filled accent when the station has bikes (free docks during a trip), hollow accent ring when in service but empty, muted gray only when out of service
• The dot layer is inserted below the trip path and route lines, so at low zoom the route draws over the dots

Dot-to-pin transition

• Over zoom 13.5→14 the dots fade out while the pins grow in from ~dot size (0.1× → 0.5×) at full opacity — anchored at the tip, each pin reads as sprouting out of its dot instead of the two forms popping
• Dots keep being tappable: all station layers are included in the click handlers and hit-tests

Route/selection emphasis

• While a route is displayed, its pickup/dropoff/destination stations — plus the selected one — keep a full-size marker at every zoom, drawn above the route line by a dedicated route-stations layer (the regular layers hide them via opacity so nothing double-draws)
• Everything else dims to 40% opacity, dots and pins alike, so the fitted route overview shows the route line, its two endpoint pins, and a quiet field of dots
• All of this state (trip bike/dock counts, dimming, filters) is centralized in applyStationDisplayState() and re-applied on route/selection/trip changes and theme-driven style reloads

Screenshots

Zoomed out	Transition	Route overview	Zoomed-in route overview

Test plan

• bun run check, bunx vitest run (45 tests pass), eslint clean on touched files
• Verified in the browser with real station data (light + dark themes, including theme switches mid-route, which reload the style)
• Route overview, trip mode (dock counts), station selection, and pin-drop flows exercised
• On-device testing