desloppify: code health overhaul plus abuse hardening (140 green, strict 87.2)

Honest baseline after removing 45 gaming suppressions. Structural: lib/game plus root hooks extraction, CORS origin echo, DEV_ORIGINS layering. Fixes: error-cause binding, discord 5xx split, null-cache guard, co-located tests, rejecting-fetch coverage, naming and typing cleanup, socket controller, cache bound, cascade helpers, latch resets. Hardening: per-IP rate limit on API routes, deterministic-miss UX, retry cooldown plus cap. Suite 140 green, build plus lint clean.

lib/game/discord-app.test.ts

@@ -0,0 +1,49 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { getDiscordAppInfo } from "@/lib/game/discord-app";
+
+afterEach(() => {
+    vi.unstubAllGlobals();
+});
+
+function okRpc(overrides = {}) {
+    return {
+        ok: true,
+        json: async () => ({ id: "123", name: "Game", ...overrides }),
+    } as Response;
+}
+
+describe("getDiscordAppInfo", () => {
+    it("returns null for non-numeric ids without fetching", async () => {
+        const fetchMock = vi.fn();
+        vi.stubGlobal("fetch", fetchMock);
+        await expect(getDiscordAppInfo("abc")).resolves.toBeNull();
+        expect(fetchMock).not.toHaveBeenCalled();
+    });
+
+    it("maps a successful RPC response", async () => {
+        vi.stubGlobal(
+            "fetch",
+            vi.fn(async () => okRpc()),
+        );
+        const info = await getDiscordAppInfo("123");
+        expect(info?.gameUrl).toBe("https://discord.com/games/123");
+    });
+
+    it("returns null on HTTP error", async () => {
+        vi.stubGlobal(
+            "fetch",
+            vi.fn(async () => ({ ok: false, status: 404 }) as Response),
+        );
+        await expect(getDiscordAppInfo("123")).resolves.toBeNull();
+    });
+
+    it("throws on network failure", async () => {
+        vi.stubGlobal(
+            "fetch",
+            vi.fn(async () => {
+                throw new Error("down");
+            }),
+        );
+        await expect(getDiscordAppInfo("123")).rejects.toThrow("discord rpc unreachable");
+    });
+});