feat: daybreak finale turns the contact arrival into a sunrise with a dawn chord

src/journey/dawn.ts

@@ -0,0 +1,21 @@
+/**
+ * END OF SHIFT: arriving at the destination ends the night. One scalar, dawn
+ * (0..1), eases in over the outro; the scene derives the sky, the sun and the
+ * grade from it, and the DOM gets a stepped html[data-dawn] so CSS can key the
+ * credit and the letterbox tint off it. Shared by the DOM and the lazy scene
+ * chunk, so it stays tiny and pure.
+ */
+export type DawnStep = 'night' | 'first-light' | 'sunrise' | 'day';
+
+/** Lower bounds of each step after night. */
+export const DAWN_STEPS = { 'first-light': 0.3, sunrise: 0.6, day: 0.95 } as const;
+
+/** The gantry plate's sub-line while parked at the destination. */
+export const END_OF_SHIFT_SUBLINE = 'END OF SHIFT · 05:48';
+
+export function dawnStep(dawn: number): DawnStep {
+  if (!(dawn >= DAWN_STEPS['first-light'])) return 'night';
+  if (dawn < DAWN_STEPS.sunrise) return 'first-light';
+  if (dawn < DAWN_STEPS.day) return 'sunrise';
+  return 'day';
+}