docs: bring every markdown file up to date with the code

The docs had drifted in ways that would mislead: DATA-MODEL documented a
localStorage shape the code stopped using (completedAt, no ignored store),
INGESTION claimed three Game8 templates when five are known, ARCHITECTURE
still listed the whole client and time.ts as unbuilt, and the review-quarantine
skill described a pipeline that does not exist yet without saying so.

Adds the parser roster and the six date formats as tables, documents the
subpath/base-href and offline behaviour, and records the new product surface
(first-run picker, ignore, offline, credit) as PRD features.

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

docs/DATA-MODEL.md

@@ -196,11 +196,19 @@ malformed row surfaces at the boundary rather than deep in the UI.
 Namespaced, versioned, and small. Nothing here ever goes to the server.
 
 ```ts
-"gacha-tracker:v1:completions"  // { [eventId]: { completedAt: string } }
-"gacha-tracker:v1:prefs"        // { region, hiddenGames[], hiddenTypes[], showCompleted }
-"gacha-tracker:v1:feedCache"    // { fetchedAt, events }  — offline fallback
+"gacha-tracker:v1:completions"  // { [eventId]: { at: string } }  — "I finished this"
+"gacha-tracker:v1:ignored"      // { [eventId]: { at: string } }  — "stop showing me this"
+"gacha-tracker:v1:prefs"        // { region, hiddenGames[], showCompleted, showIgnored,
+                                //   regionConfirmed, onboarded }
 ```
 
+Completions and ignores are the same shape and share one implementation
+(`useMarkSet`), but stay in separate stores because they mean different things: a completed event is
+dimmed and still counted, an ignored one disappears from both views.
+
+Offline caching is the service worker's job, not localStorage's — it caches the feed response
+itself, so there is no second copy of the events to keep in sync.
+
 The `v1` segment is the migration hook. On boot, the client checks for keys at older versions and
 migrates them forward before reading. **Never delete an old-version key until the migration has
 shipped and run** — a user who has not opened the app in six months still has their data under the
@@ -213,14 +221,16 @@ old key.
   "format": "gacha-tracker-export",
   "version": 1,
   "exportedAt": "2026-08-14T12:00:00.000Z",
-  "completions": { "genshin:windblume-festival:2026-03-14": { "completedAt": "..." } },
-  "prefs": { "region": "europe", "hiddenGames": [] }
+  "completions": { "genshin:windblume-festival:2026-03-14": { "at": "..." } },
+  "ignored": { "zzz:some-event-i-skip:2026-08-19": { "at": "..." } },
+  "prefs": { "region": "europe", "hiddenGames": [], "onboarded": true }
 }
 ```
 
-Import **merges**: a completion present in either the file or the current device stays completed.
-Import never removes a completion. Losing a user's marks to a bad import is unrecoverable, so the
-merge is deliberately one-directional.
+Import **merges** both sets: a mark present in either the file or the current device survives, and
+import never removes one. Losing a user's marks to a bad import is unrecoverable, so the merge is
+deliberately one-directional. A file whose `format` is unrecognised is refused outright rather than
+partly applied.
 
 ## Schema versioning