Add per-day map coloring and remaining unit tests

- RouteMapThumbnail: Color route segments per day with alternating colors
  when dayBreaks are present, pass through from route detail page
- overnight.test.ts: 6 tests for isOvernight/setOvernight with Y.Doc
- daybreaks-extraction.test.ts: 3 tests for GPX → dayBreaks index extraction

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/gpx/src/daybreaks-extraction.test.ts

@@ -0,0 +1,68 @@
+import { describe, it, expect } from "vitest";
+import { generateGpx } from "./generate.ts";
+import { parseGpxAsync } from "./parse.ts";
+
+/**
+ * Tests the dayBreaks extraction pattern used by the Journal's updateRoute:
+ * parse GPX → find waypoints with isDayBreak → extract indices
+ */
+describe("dayBreaks extraction from GPX", () => {
+  it("extracts empty dayBreaks when no overnight waypoints", async () => {
+    const gpx = generateGpx({
+      waypoints: [
+        { lat: 52.52, lon: 13.405, name: "Berlin" },
+        { lat: 50.98, lon: 11.028, name: "Erfurt" },
+      ],
+      tracks: [[
+        { lat: 52.52, lon: 13.405, ele: 34 },
+        { lat: 50.98, lon: 11.028, ele: 195 },
+      ]],
+    });
+    const parsed = await parseGpxAsync(gpx);
+    const dayBreaks = parsed.waypoints
+      .map((w, i) => (w.isDayBreak ? i : -1))
+      .filter((i) => i >= 0);
+    expect(dayBreaks).toEqual([]);
+  });
+
+  it("extracts single dayBreak index", async () => {
+    const gpx = generateGpx({
+      waypoints: [
+        { lat: 52.52, lon: 13.405, name: "Berlin" },
+        { lat: 51.84, lon: 12.243, name: "Dessau", isDayBreak: true },
+        { lat: 50.98, lon: 11.028, name: "Erfurt" },
+      ],
+      tracks: [[
+        { lat: 52.52, lon: 13.405, ele: 34 },
+        { lat: 51.84, lon: 12.243, ele: 80 },
+        { lat: 50.98, lon: 11.028, ele: 195 },
+      ]],
+    });
+    const parsed = await parseGpxAsync(gpx);
+    const dayBreaks = parsed.waypoints
+      .map((w, i) => (w.isDayBreak ? i : -1))
+      .filter((i) => i >= 0);
+    expect(dayBreaks).toEqual([1]);
+  });
+
+  it("extracts multiple dayBreak indices", async () => {
+    const gpx = generateGpx({
+      waypoints: [
+        { lat: 0, lon: 0, name: "A" },
+        { lat: 1, lon: 0, name: "B", isDayBreak: true },
+        { lat: 2, lon: 0, name: "C" },
+        { lat: 3, lon: 0, name: "D", isDayBreak: true },
+        { lat: 4, lon: 0, name: "E" },
+      ],
+      tracks: [[
+        { lat: 0, lon: 0 }, { lat: 1, lon: 0 }, { lat: 2, lon: 0 },
+        { lat: 3, lon: 0 }, { lat: 4, lon: 0 },
+      ]],
+    });
+    const parsed = await parseGpxAsync(gpx);
+    const dayBreaks = parsed.waypoints
+      .map((w, i) => (w.isDayBreak ? i : -1))
+      .filter((i) => i >= 0);
+    expect(dayBreaks).toEqual([1, 3]);
+  });
+});