feat(github): show relative dates in pull requests

Pull request lists, timelines, commits and replies show how long ago
something happened ("just now", "8 hours ago", "yesterday", "3 days ago")
and the date after 30 days ("on Oct 12"). Hovering a timeline date shows
the full date and time. With pretty formatting off, the plain date and time
are shown.

src/features/github/ui/ui.test.tsx

@@ -6,27 +6,28 @@ import { Avatar, AvatarStack, avatarSrc, reviewerRingColor } from "./Avatar";
 import { BranchChip, LabelChip, StateTag, labelForeground } from "./chips";
 import { ChooserPopup, chooserItems } from "./ChooserPopup";
 import { Markdown } from "./Markdown";
-import { prettyDate, prettyDateTime } from "./prettyDate";
+import { fullDateTime, prettyDate } from "./prettyDate";
 
 describe("prettyDate", () => {
   const o = { ...DEFAULT_DATE_FORMAT, overrideSystem: true, pattern: "dd.MM.yyyy", use24Hour: true };
-  const now = new Date(2026, 9, 30, 15, 0).getTime();
+  const now = new Date(2026, 9, 31, 9, 2).getTime();
 
-  it("formats like DateFormatUtil.formatPrettyDate", () => {
-    expect(prettyDate(now - 20_000, now, o)).toBe("Moments ago");
+  it("formats relative dates like GitHub", () => {
+    expect(prettyDate(now - 20_000, now, o)).toBe("just now");
+    expect(prettyDate(now + 20_000, now, o)).toBe("just now");
     expect(prettyDate(now - 60_000, now, o)).toBe("1 minute ago");
     expect(prettyDate(now - 42 * 60_000, now, o)).toBe("42 minutes ago");
-    expect(prettyDate(now - 3 * 3_600_000, now, o)).toBe("Today");
-    expect(prettyDate(new Date(2026, 9, 29, 9, 5).getTime(), now, o)).toBe("Yesterday");
-    expect(prettyDate(new Date(2026, 8, 2, 9, 5).getTime(), now, o)).toBe("02.09.2026");
+    expect(prettyDate(now - 3_600_000, now, o)).toBe("1 hour ago");
+    expect(prettyDate(new Date(2026, 9, 31, 0, 27).getTime(), now, o)).toBe("8 hours ago");
+    expect(prettyDate(new Date(2026, 9, 30, 8, 0).getTime(), now, o)).toBe("yesterday");
+    expect(prettyDate(new Date(2026, 9, 21, 9, 5).getTime(), now, o)).toBe("9 days ago");
+    expect(prettyDate(new Date(2026, 8, 2, 9, 5).getTime(), now, o)).toBe("on 02.09.2026");
     expect(prettyDate("not a date", now, o)).toBe("");
   });
 
-  it("adds the time with formatPrettyDateTime, and honours pretty formatting off", () => {
-    expect(prettyDateTime(new Date(2026, 9, 30, 9, 5).getTime(), now, o)).toBe("Today 09:05");
-    expect(prettyDateTime(new Date(2026, 9, 29, 9, 5).getTime(), now, o)).toBe("Yesterday 09:05");
-    expect(prettyDateTime(new Date(2026, 8, 2, 9, 5).getTime(), now, o)).toBe("02.09.2026 09:05");
-    expect(prettyDate(now - 20_000, now, { ...o, pretty: false })).toBe("30.10.2026");
+  it("shows the plain date and time with pretty formatting off", () => {
+    expect(prettyDate(now - 20_000, now, { ...o, pretty: false })).toBe("31.10.2026 09:01");
+    expect(fullDateTime(new Date(2026, 9, 31, 0, 27).getTime(), o)).toBe("31.10.2026 00:27");
   });
 });