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>

apps/planner/app/lib/overnight.test.ts

@@ -0,0 +1,80 @@
+import { describe, it, expect } from "vitest";
+import * as Y from "yjs";
+import { setOvernight, isOvernight } from "./overnight.ts";
+import type { YjsState } from "./use-yjs.ts";
+
+function createTestYjs(): YjsState {
+  const doc = new Y.Doc();
+  const waypoints = doc.getArray<Y.Map<unknown>>("waypoints");
+  return { doc, waypoints } as unknown as YjsState;
+}
+
+function addWaypoint(yjs: YjsState, lat: number, lon: number): void {
+  const yMap = new Y.Map();
+  yMap.set("lat", lat);
+  yMap.set("lon", lon);
+  yjs.waypoints.push([yMap]);
+}
+
+function createDocMap(): Y.Map<unknown> {
+  const doc = new Y.Doc();
+  const arr = doc.getArray<Y.Map<unknown>>("test");
+  const yMap = new Y.Map<unknown>();
+  arr.push([yMap]);
+  return yMap;
+}
+
+describe("isOvernight", () => {
+  it("returns false for a waypoint without overnight flag", () => {
+    const yMap = createDocMap();
+    yMap.set("lat", 52.52);
+    yMap.set("lon", 13.405);
+    expect(isOvernight(yMap)).toBe(false);
+  });
+
+  it("returns true for a waypoint with overnight flag", () => {
+    const yMap = createDocMap();
+    yMap.set("lat", 52.52);
+    yMap.set("lon", 13.405);
+    yMap.set("overnight", true);
+    expect(isOvernight(yMap)).toBe(true);
+  });
+
+  it("returns false for non-boolean overnight value", () => {
+    const yMap = createDocMap();
+    yMap.set("overnight", "yes");
+    expect(isOvernight(yMap)).toBe(false);
+  });
+});
+
+describe("setOvernight", () => {
+  it("sets overnight flag on a waypoint", () => {
+    const yjs = createTestYjs();
+    addWaypoint(yjs, 52.52, 13.405);
+
+    setOvernight(yjs, 0, true);
+
+    const yMap = yjs.waypoints.get(0)!;
+    expect(yMap.get("overnight")).toBe(true);
+  });
+
+  it("clears overnight flag from a waypoint", () => {
+    const yjs = createTestYjs();
+    addWaypoint(yjs, 52.52, 13.405);
+
+    setOvernight(yjs, 0, true);
+    expect(yjs.waypoints.get(0)!.get("overnight")).toBe(true);
+
+    setOvernight(yjs, 0, false);
+    expect(yjs.waypoints.get(0)!.get("overnight")).toBeUndefined();
+  });
+
+  it("does nothing for out-of-bounds index", () => {
+    const yjs = createTestYjs();
+    addWaypoint(yjs, 52.52, 13.405);
+
+    // Should not throw
+    setOvernight(yjs, 5, true);
+    expect(yjs.waypoints.get(0)!.get("overnight")).toBeUndefined();
+  });
+});