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]>

src/ingest/adapters/index.ts

@@ -66,6 +66,12 @@ const SOURCES: SourceSpec[] = [
     url: "https://game8.co/games/Neverness-to-Everness/archives/592073",
     parserId: "game8",
   },
+  {
+    id: "nikki-game8-events",
+    game: "nikki",
+    url: "https://game8.co/games/Infinity-Nikki/archives/487445",
+    parserId: "game8",
+  },
 ];
 
 function toAdapter(spec: SourceSpec): Adapter {