feat(points): balance, history and shop page

Add /points page with wallet balance, shop grouped by slot and ledger
history with game names. The wallet loads once in PreferencesContext after
login, so the header shows a balance chip and the link. Premium accents
gold and teal override the free accent while equipped. German and English.

README.md

@@ -31,6 +31,9 @@ To Be Played is split into three repositories:
 - **Your stats** (`/stats`): totals and statuses; the pile in hours, in weeks at your pace of the last 90 days and in
   years of full-time work, and its oldest unplayed game; most played and most loyal games; top genres and moods;
   trips to the moon, the longest gaming day, games started but under one hour; finished games per year; games per platform.
+- **Pile Points** (`/points`): points for playing games off your pile (start, finish by time to beat, 100 %, month and
+  streak bonuses; Core checks proof of play), spent in a small shop on an avatar border, a badge, a premium accent and a
+  banner frame, shown on the dashboard and the public profile. The balance is in the header.
 - **Landing page**: next to the community numbers and the top games, three blocks: games per platform, top genres and
   finished games per year of all users.
 - **Library**: status filters, "short games" filter (up to 10 h), search, sorting by playtime, recently seen, newest