style(274): retune the dark transect palette

Colour choices for the dark palette, made while previewing in the Studio:
- roadCovered #9dcde4 -> #fdb021 (the covered road now reads amber)
- bridge #79d1c5 -> #9be9de
- place / railway #129252 -> #68ad7f
- shrine #b32c2c -> #a05050
- other #ff9900 -> #a7b7d6

The light palette is unchanged.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PLt25nCVMsoroKALYUBu6u

src/song-274/palette.ts

@@ -40,15 +40,15 @@ export type FeatureFamily =
 export const darkPalette: TransectPalette = {
   background: "#28323d", // --paper
   roadAhead: "#49565f", // --rule
-  roadCovered: "#9dcde4", // --road
-  bridge: "#79d1c5", // --bridge
+  roadCovered: "#fdb021", // --road
+  bridge: "#9be9de", // --bridge
   tunnel: "#b6c5c1", // --tunnel
   shed: "#eba9eb", // --shed
   watercourse: "#5FB6D6", // --water
-  place: "#129252", // --place
-  railway: "#129252", // --railway
-  shrine: "#b32c2c", // --shrine
-  other: "#ff9900", // --util
+  place: "#68ad7f", // --place
+  railway: "#68ad7f", // --railway
+  shrine: "#a05050", // --shrine
+  other: "#a7b7d6", // --util
 };
 
 export const lightPalette: TransectPalette = {