feat: add badge system with 10 achievement tiers

lib/badges.ts

@@ -0,0 +1,23 @@
+export type Badge = { name: string; file: string; threshold: number };
+
+export const BADGES: Badge[] = [
+  { name: "Omniscient",   file: "omniscient",   threshold: 10000 },
+  { name: "Transcendant", file: "transcendant", threshold: 5000  },
+  { name: "Mythique",     file: "mythique",     threshold: 2500  },
+  { name: "Légende",      file: "légende",      threshold: 1000  },
+  { name: "Maître",       file: "maître",       threshold: 500   },
+  { name: "Expert",       file: "expert",       threshold: 150   },
+  { name: "Adepte",       file: "adepte",       threshold: 50    },
+  { name: "Initié",       file: "initié",       threshold: 20    },
+  { name: "Apprenti",     file: "apprenti",     threshold: 5     },
+  { name: "Novice",       file: "novice",       threshold: 0     },
+];
+
+export function getBadge(wins: number): Badge {
+  return BADGES.find((b) => wins >= b.threshold) ?? BADGES[BADGES.length - 1];
+}
+
+export function getNextBadge(wins: number): Badge | null {
+  const idx = BADGES.findIndex((b) => wins >= b.threshold);
+  return idx > 0 ? BADGES[idx - 1] : null;
+}