feat(enakgame): weekly leaderboard

GET /customer/enakgame/leaderboard ranks the customers of an organization by
the EnakCoin they won from games in one week, Monday to Sunday in
Asia/Jakarta. Only completed, unflagged sessions count, by the week they
started; entry cost is not subtracted. Equal totals rank by who reached
theirs first, so no two customers share a rank.

Optional date (any day of the week, this week by default), game_id and limit
(10, at most 100). The response holds the top ranks and, under me, the
customer asking wherever they rank. Other customers are shown by a masked
name: the first word whole, the others by their first letter; a word with a
digit keeps only its first character.

The EnakGame web game shows it: integration-enakgame.md §10 (checklist now
§11) and RFC §11. The DB test needs TEST_DATABASE_URL.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/rfc-enakgame.md

@@ -843,6 +843,7 @@ tambahkan snapshot harian, bukan cache yang di-invalidate.
 | `POST` | `/sessions/:id/complete` | §7.2. Idempotent tanpa header |
 | `GET` | `/sessions/:id` | Status dan hasil |
 | `GET` | `/sessions` | Riwayat main; filter opsional `game_id`, `status` (dipakai game untuk menemukan session `STARTED` setelah reload) |
+| `GET` | `/leaderboard` | Peringkat mingguan (Senin–Minggu, Asia/Jakarta) org customer menurut EnakCoin yang dimenangkan dari game. Query opsional `date` (hari mana pun dalam minggu itu), `game_id`, `limit` (default 10, maks 100) |
 
 Prefix `/enakgame` dipakai karena `/customer/games` sudah dipakai alur spin lama.
 
@@ -940,7 +941,8 @@ Ditemukan saat memetakan code. Tidak memblokir RFC ini, tapi sebagian berdampak
 ## 16. Di Luar Scope
 
 - **Mission** (PRD §3.1, §19). PRD belum mendefinisikan aturannya.
-- **Leaderboard** (PRD §15).
+- **Leaderboard event** (PRD §15). Leaderboard mingguan umum sudah ada (§11, ditambahkan
+  2026-10-12); leaderboard per event dengan aturannya sendiri belum.
 - **Reward `TIERED`** (§8).
 - **Budget Controller automatic mode** (D9).
 - **Hosting dan build Phaser.** RFC ini hanya mendefinisikan API yang dipanggil game.