[playersettings] Drop Growth.YIR telemetry and MakerPenSessionCount on write (#145)

* [playersettings] drop Growth.YIR telemetry on write

The client posts its Year-In-Review counters (Growth.YIR.UGC.TubeDistance,
Growth.YIR.DistanceTraveled, …) through PUT /playersettings with a new value every time,
so the change-detection dedupe never skips them. A two-minute tail at ~500 CCU showed
them as about half of all KV writes (3.7 writes/s overall, 448 writes from 448 PUTs).
Nothing server-side reads them and the client has none for a new player, so a PUT naming
one is answered 200 and nothing is stored. Keys stay unseeded for a player whose only
posts are telemetry.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

* [playersettings] also drop MakerPenSessionCount

A per-session counter the client bumps on every post, like the Growth.YIR telemetry; nothing
reads it. The maker pen PREFERENCES (MakerPen_SnappingMode and the other MakerPen_* keys) are
kept — the client reads those back.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

apps/playersettings/README.md

@@ -22,6 +22,13 @@ Player-settings worker served on the `playersettings` subdomain.
 > Emptying the map with DELETE puts the player back to a first read: the next
 > `GET` re-seeds the defaults.
 
+> Keys under `Growth.YIR.` (the client's Year-In-Review telemetry — distance
+> drawn, time with friends, …) and `MakerPenSessionCount` are **dropped** on
+> `PUT`, not stored. The client posts them with a new value every time, so they
+> were over half of all writes and nothing reads them. Real maker pen preferences
+> (`MakerPen_SnappingMode`, …) are kept. See `IGNORED_SETTING_KEYS` /
+> `IGNORED_SETTING_PREFIXES` in `default-settings.ts`.
+
 ## KV namespace
 
 ```sh