feat(rewards): ledger, earning rules and nightly settle

New module rewards tracks Pile Points in an append-only ledger. A settle
derives rows from the status log, playtime days and achievements, once per
user, kind and game. The balance is the sum of all rows. Settle runs on
every wallet read and nightly at 02:30. The unique key (user_id, kind, ref)
makes every run idempotent. V26 also pays a one-time starter grant for
finishes from before the status log.

readme.md

@@ -57,6 +57,13 @@ To Be Played is split into three repositories:
 - **Status history**: a database trigger logs every status change of a library game in `user_game_status_change`
   (old and new status, time, whether the user chose it), whatever code path made it. It starts with V14; older
   changes are not known.
+- **Pile Points** (`modules/rewards`): users earn points for playing games off the pile, in an append-only ledger
+  (`reward_ledger`, V26; the balance is the sum). No code path pays: a settle (on `GET /api/rewards/wallet` and
+  nightly at 02:30, `app.rewards.settle-cron`) derives rows from the status log, playtime days, achievements and pile
+  snapshots, once per user, kind and game (`ref`). Rules and numbers: `RewardRules`; a Steam finish needs playtime and one
+  proof of fresh play (ending achievement or playtime around the finish, or half of the IGDB time played since the finish; old history pays nothing). The month bonus needs a finished game in that month. Games added by hand pay 15 for
+  a finish, at most 3 per ISO week. The settle takes a per-user advisory lock. V26 also pays a one-time starter grant
+  for finishes from before the status log.
 - **Wishlist**: synced from Steam with store price and discount.
 - **Broken image repair**: the frontend reports a Steam cover or achievement icon that does not load. At 01:30
   (Europe/Berlin) a job checks up to 200 reports. A cover that loads again is left alone; else the store's hashed
@@ -114,6 +121,7 @@ ArchUnit role rules (`RoleAnnotationRules`) and `src/test/resources/contract/aut
 
 | Method | Path | Auth |
 |---|---|---|
+| `GET` | `/api/rewards/wallet` (balance, catalog, owned, equipped, last 50 ledger rows with the game name) | JWT |
 | `GET` | `/api/library/games`, `/api/library/games/{appid}` | JWT |
 | `PATCH` | `/api/library/games/{appid}/backlog` (only the sent fields; `null` clears one) | JWT |
 | `PUT`, `DELETE` | `/api/library/games/{appid}/corrections/{field}` (`{value}`; `name`, `image`, `speedrun`, `moods`, `endless`, `genres`; `204`, `400 INVALID_CORRECTION`) | JWT, AUDITOR |
@@ -165,6 +173,7 @@ flowchart LR
         Stats["stats"]
         Version["version"]
         Account["account"]
+        Rewards["rewards"]
         Steam["steam_adapter"]
         Igdb["igdb_adapter"]
         Speedrun["speedrun_adapter"]
@@ -173,6 +182,7 @@ flowchart LR
         LibService --> Speedrun
     end
     Browser -->|"tbp_access cookie"| Security
+    Rewards --> Db
     Security -->|"JWKS by kid"| Auth["ToBePlayed-Auth"]
     Steam --> SteamApi["Steam Web API"]
     Steam -->|"HEAD"| SteamCdn["Steam CDN"]