feat: add shared rarity config and helpers

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

shared/lib/rarity.test.ts

@@ -0,0 +1,31 @@
+import { describe, it, expect } from "bun:test";
+import { getRarityConfig, RARITY_CONFIG, defaultName } from "./rarity";
+
+describe("getRarityConfig", () => {
+  it("returns correct config for known rarities", () => {
+    expect(getRarityConfig("SSR").color).toBe(0xF1C40F);
+    expect(getRarityConfig("SSR").emoji).toBe("🌟");
+    expect(getRarityConfig("SSR").label).toBe("SSR");
+  });
+
+  it("returns correct config for loot types", () => {
+    expect(getRarityConfig("CURRENCY").color).toBe(0x2ECC71);
+    expect(getRarityConfig("XP").color).toBe(0x1ABC9C);
+    expect(getRarityConfig("NOTHING").color).toBe(0x636363);
+  });
+
+  it("falls back to Common for unknown rarity", () => {
+    const result = getRarityConfig("LEGENDARY");
+    expect(result).toEqual(RARITY_CONFIG["C"]);
+  });
+});
+
+describe("defaultName", () => {
+  it("extracts filename from path", () => {
+    expect(defaultName("/assets/items/sword.png")).toBe("sword.png");
+  });
+
+  it("returns image.png for empty path", () => {
+    expect(defaultName("")).toBe("image.png");
+  });
+});

shared/lib/rarity.ts

@@ -0,0 +1,17 @@
+export const RARITY_CONFIG: Record<string, { color: number; emoji: string; label: string }> = {
+  C:        { color: 0x95A5A6, emoji: "📦", label: "Common" },
+  R:        { color: 0x3498DB, emoji: "📦", label: "Rare" },
+  SR:       { color: 0x9B59B6, emoji: "✨", label: "Super Rare" },
+  SSR:      { color: 0xF1C40F, emoji: "🌟", label: "SSR" },
+  CURRENCY: { color: 0x2ECC71, emoji: "💰", label: "Currency" },
+  XP:       { color: 0x1ABC9C, emoji: "🔮", label: "Experience" },
+  NOTHING:  { color: 0x636363, emoji: "💨", label: "Empty" },
+};
+
+export function getRarityConfig(rarity: string): { color: number; emoji: string; label: string } {
+  return RARITY_CONFIG[rarity] ?? RARITY_CONFIG["C"];
+}
+
+export function defaultName(path: string): string {
+  return path.split("/").pop() || "image.png";
+}