map: markers legible on both the white and the dark blueprint

Markers sit on two very different surfaces - the light blueprint on white and
the dark blueprint over the near-black navy card - but the palette only ever
suited one. The grey "no subtype" default sat at 1.88:1 against white and the
orange asset-type step at 2.16:1, so both effectively disappeared on the light
blueprint. The fixed white ring made it worse: on white it added nothing.

Re-step the asset-type colors to versions of the SAME hues that clear 3:1
against both surfaces, replace the grey default with a neutral that clears
5.4:1 / 3.7:1, and derive the ring from the fill's luminance (light fill ->
dark ring, dark fill -> light ring) so every marker keeps a hard edge on
either background. The ring also rescues a washed-out color a user picks by
hand for a subtype, which no palette change can reach. The PDF export applies
the same rule to its markers and legend swatches, keeping print in parity.

Colors were chosen against a contrast/CVD validator rather than by eye. Note
that five simultaneous hues cannot all stay distinguishable under color-blind
simulation - past roughly five subtypes on screen, the legend and the hover
tooltip carry identity.

Adds computed contrast assertions so a future palette edit cannot
reintroduce a washed-out step.

frontend/src/components/ShopFloorMap.vue

@@ -97,7 +97,7 @@ import L from 'leaflet'
 import 'leaflet/dist/leaflet.css'
 import { loadMapConfig, blueprintUrlFor, state as mapConfig } from '../composables/mapConfig'
 import { assetTypeLabel, assetDetailRoute } from '../utils/assetTypes'
-import { getSubtypeId } from '../utils/mapColors'
+import { getSubtypeId, markerRingColor, UNSPECIFIED_COLOR } from '../utils/mapColors'
 import api from '../api'
 
 const props = defineProps({
@@ -451,7 +451,7 @@ function renderMarkers() {
       // Unified asset mode - use subtype colors when a type is selected
       if (props.selectedAssetType) {
         const subtypeId = getSubtypeId(item)
-        color = (subtypeId && props.subtypeColors[subtypeId]) || '#BDBDBD'
+        color = (subtypeId && props.subtypeColors[subtypeId]) || UNSPECIFIED_COLOR
         typeName = (subtypeId && props.subtypeNames[subtypeId]) || item.assettype || ''
       } else {
         // Prefer the stored AssetType.color; fall back to the built-in map.
@@ -477,7 +477,9 @@ function renderMarkers() {
     const marker = L.circleMarker([leafletY, leafletX], {
       radius: 6,
       fillColor: color,
-      color: 'rgba(255,255,255,0.8)',
+      // Ring picked from the fill, not fixed white - a white ring on a light
+      // marker vanished against the light (white) blueprint.
+      color: markerRingColor(color),
       weight: 2,
       fillOpacity: 1,
       renderer: canvasRenderer