feat(nikki): track Infinity Nikki

Adds the game and its Game8 events page. One `SOURCES` entry against the
existing game8 parser, plus one date shape that page needs:
`parseLabelledStartEnd` reads a duration cell holding `Start: <date>` and
`End: <date>` split by a `<br>`, which a tag-stripping reader flattens
into one run of text.

Four of the seven events say `End: Permanent`. That is the source telling
us there is no deadline, so they publish with `endsAt: null` and
`endPrecision: "unknown"` rather than a plausible date. The labelled cell
is also structure end to end, so it never becomes a summary — stripping
the leading half would leave "End: Permanent" standing where a
description belongs.

Verified by re-extracting the page with a throwaway script independent of
the parser: 7 rows in, 7 events out, every date matching.

Note the source itself is stale — its "Current Events" table still lists
January-May 2025 and "Upcoming Events" says there are none. The adapter is
right; the page looks abandoned, and Nikki coverage worth relying on needs
a second source at a higher priority.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

test/dates.test.ts

@@ -1,6 +1,7 @@
 import { describe, expect, test } from "bun:test";
 import {
   parseFullRange,
+  parseLabelledStartEnd,
   parseMonthDayRange,
   parseMonthDayYear,
   parseOpenRange,
@@ -127,3 +128,39 @@ describe("parseOpenRange", () => {
     expect(parseOpenRange("Releases in Version 3.6")).toBeNull();
   });
 });
+
+describe("parseLabelledStartEnd", () => {
+  test("reads a labelled cell", () => {
+    expect(
+      parseLabelledStartEnd("Start: April 28, 2025 End: June 12, 2025"),
+    ).toEqual({
+      start: { iso: "2025-04-28T00:00:00.000Z", precision: "day" },
+      end: { iso: "2025-06-12T00:00:00.000Z", precision: "day" },
+    });
+  });
+
+  test("reports no end when the end half is not a date", () => {
+    // "Permanent" is the source telling us there is no deadline. Inventing one
+    // is the failure this codebase exists to prevent.
+    const permanent = parseLabelledStartEnd(
+      "Start: January 24, 2025 End: Permanent",
+    );
+    expect(permanent?.start.iso).toBe("2025-01-24T00:00:00.000Z");
+    expect(permanent?.end).toBeNull();
+
+    expect(parseLabelledStartEnd("Start: January 24, 2025 End: TBD")?.end).toBeNull();
+    expect(parseLabelledStartEnd("Start: January 24, 2025")?.end).toBeNull();
+  });
+
+  test("returns null when the start half is not a date", () => {
+    expect(parseLabelledStartEnd("Start: After maintenance End: TBD")).toBeNull();
+    expect(parseLabelledStartEnd("Ends after 30 days of making your account.")).toBeNull();
+  });
+
+  test("requires the colons, so prose containing 'end' does not split", () => {
+    // Without them, any sentence mentioning an end would look like a boundary.
+    expect(
+      parseLabelledStartEnd("Start the quest before August 12, 2026 to end the arc"),
+    ).toBeNull();
+  });
+});