feat(web): log of reads, plays, watches and listens, by month

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/test/labels.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, test } from "bun:test";
 import type { ChangeEvent } from "../src/api.ts";
-import { changeValue, describeChange, groupByRun, scheduleLabel, SCHEDULES } from "../src/labels.ts";
+import { changeValue, describeChange, groupByRun, logMonth, scheduleLabel, SCHEDULES } from "../src/labels.ts";
 
 const base: ChangeEvent = {
   id: "ev1",
@@ -117,3 +117,12 @@ describe("changeValue", () => {
     expect(changeValue("review", "x".repeat(300), "5half")).toHaveLength(160);
   });
 });
+
+describe("logMonth", () => {
+  test("month headings from partial dates and timestamps", () => {
+    expect(logMonth("2026-10-01")).toBe("October 2026");
+    expect(logMonth("2025-03")).toBe("March 2025");
+    expect(logMonth("2019")).toBe("2019");
+    expect(logMonth("2026-01-31T23:59:00.000Z")).toBe("January 2026");
+  });
+});