docs: correct the counts three docs had drifted past

Each of these was true when written and stopped being true when a source
landed. dates.ts holds ten formats, not nine; INGESTION says Game8 uses
"at least four page templates" directly above a list of seven; its testing
note still credits "both current adapters" when there are eleven; PRD
lists the seven launch games against ten in GameId. AGENTS also missed
fandom from the parsers-are-keyed-by-site bullet and build-static.ts from
the tree, which matters because another section leans on the latter.

The PRD table stays as launch scope rather than becoming a roster to keep
in sync — GameId is named as the live answer instead, which is the same
move that keeps this drift from recurring. Its no-schema-change claim is
sharpened to name GachaEvent, because Reverse: 1999 did add a field:
resetHourLocal, to game metadata, which moves no stored key. The claim as
written read as false against a commit that plainly added one.

Also draws sanitize into the stage diagram as 2.5. It runs on every source
without the pipeline arranging it, which is exactly why it kept being
absent from the picture.

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

docs/PRD.md

@@ -45,9 +45,16 @@ event, because a missing event sends them to a wiki while a wrong one makes them
 | Arknights: Endfield | `endfield` |
 | Neverness to Everness | `nte` |
 
-Adding a game must require no schema change — only a `GameId` entry and a source registration.
-That is the test of whether the data model is right. A game may have several sources; see
-`docs/INGESTION.md` § Three layers.
+Added since launch, on the strength of the release thread (`docs/FEEDBACK.md` § P1): Infinity Nikki
+(`nikki`), Persona 5: The Phantom X (`p5x`), Reverse: 1999 (`r1999`). **`GameId` in
+`src/shared/schema.ts` is the live answer** and `SOURCES` says which of them actually have a source —
+this table is the launch scope, not a roster to keep in sync.
+
+Adding a game must require no change to `GachaEvent` — only a `GameId` entry, its `games.ts`
+metadata, and a source registration. That is the test of whether the data model is right, and it has
+held: the ten games here have cost the event schema nothing. Per-game *metadata* does occasionally
+grow (Reverse: 1999 needed `resetHourLocal` for a 05:00 reset), which is a different file and moves
+no stored key. A game may have several sources; see `docs/INGESTION.md` § Three layers.
 
 ### Features