docs: record the two new sources and the shapes they added

Nine sources across eight games now, two more Game8 page shapes, two more
date formats, and the h4 rule that neither game's page can be read
without.

Also notes what the two new games do *not* have: no `resetOffsets` entry,
so both take the regional default. Neither source states a server map, and
`resetOffsets` feeds `dayKey`, which is a localStorage key — so that is
recorded as an assumption to confirm rather than left to look like a
verified fact.

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

docs/DATA-MODEL.md

@@ -9,7 +9,7 @@
 import { z } from "zod";
 
 export const GameId = z.enum([
-  "genshin", "hsr", "zzz", "wuwa", "arknights", "endfield", "nte",
+  "genshin", "hsr", "zzz", "wuwa", "arknights", "endfield", "nte", "nikki", "p5x",
 ]);
 
 export const EventType = z.enum([
@@ -254,9 +254,15 @@ reader cannot see.
 | Game | Reset (server local) | Server offset | Reset (UTC) | Copenhagen, summer / winter |
 |---|---|---|---|---|
 | Genshin, Star Rail, ZZZ, Wuwa, NTE | 04:00 | region (EU = UTC+1) | 03:00 | 05:00 / 04:00 |
+| Infinity Nikki, P5X | 04:00 | region (assumed) | 03:00 | 05:00 / 04:00 |
 | Endfield, Europe | 04:00 | UTC-5 (on the Americas server) | 09:00 | 11:00 / 10:00 |
 | Endfield, Asia / Americas | 04:00 | regional default | 20:00 / 09:00 | — |
 
+Infinity Nikki and P5X carry **no `resetOffsets` entry**, so they take the regional default. That is
+an assumption, not a verified server map — neither source states one. Confirm it against the games
+before relying on it, and note that adding an override later re-labels the game-day of ticks readers
+have already logged, which is the change this table warns about below.
+
 These server offsets are **fixed and do not observe DST**, so the reader's local reset time moves by
 an hour across the European clock change while the UTC instant stays put.