fix: apply crystal multiplier to boss rewards, steepen prestige threshold, fix stale upgrade race condition, and fix companion format display

Closes #221
Closes #222
Closes #201
Closes #213

apps/web/test/format.spec.ts

@@ -8,7 +8,7 @@
  * @author Naomi Carrigan
  */
 import { describe, expect, it } from "vitest";
-import { formatNumber } from "../src/utils/format.js";
+import { formatInteger, formatNumber } from "../src/utils/format.js";
 
 describe("formatNumber", () => {
   describe("edge cases", () => {
@@ -142,3 +142,59 @@ describe("formatNumber", () => {
     });
   });
 });
+
+describe("formatInteger", () => {
+  describe("edge cases", () => {
+    it("should return '0' for NaN", () => {
+      expect(formatInteger(Number.NaN)).toBe("0");
+    });
+
+    it("should return '0' for Infinity", () => {
+      expect(formatInteger(Infinity)).toBe("0");
+    });
+
+    it("should format negative integers with a leading minus sign", () => {
+      expect(formatInteger(-1500)).toBe("-1K");
+    });
+
+    it("should format zero as '0'", () => {
+      expect(formatInteger(0)).toBe("0");
+    });
+
+    it("should format small integers without decimals", () => {
+      expect(formatInteger(42)).toBe("42");
+    });
+  });
+
+  describe("named suffixes", () => {
+    it("should format thousands with K suffix and no decimals", () => {
+      expect(formatInteger(1500)).toBe("1K");
+    });
+
+    it("should format millions with M suffix and no decimals", () => {
+      expect(formatInteger(2_500_000)).toBe("2M");
+    });
+
+    it("should format billions with B suffix", () => {
+      expect(formatInteger(3_000_000_000)).toBe("3B");
+    });
+
+    it("should format trillions with T suffix", () => {
+      expect(formatInteger(1e12)).toBe("1T");
+    });
+
+    it("should format quintillions with Qi suffix", () => {
+      expect(formatInteger(1e18)).toBe("1Qi");
+    });
+  });
+
+  describe("letter suffixes", () => {
+    it("should format values >= 1e36 with letter suffix 'a'", () => {
+      expect(formatInteger(1e36)).toBe("1a");
+    });
+
+    it("should format values >= 1e39 with letter suffix 'b'", () => {
+      expect(formatInteger(1e39)).toBe("1b");
+    });
+  });
+});