feat: add web testing foundation with infra-backed suites (#349)

* feat: add web test framework with infra-backed suites

* fix: honor DATABASE_URL env in integration prepare script

* fix: apply web test review feedback

* fix: streamline web test infra lifecycle and workflow scope

apps/web/src/server/utils/idempotency.unit.test.ts

@@ -0,0 +1,30 @@
+import { describe, expect, it } from "vitest";
+import { canonicalizePayload } from "~/server/utils/idempotency";
+
+describe("canonicalizePayload", () => {
+  it("generates same hash for different key ordering", () => {
+    const payloadA = { b: 1, a: { y: 2, x: 1 } };
+    const payloadB = { a: { x: 1, y: 2 }, b: 1 };
+
+    const a = canonicalizePayload(payloadA);
+    const b = canonicalizePayload(payloadB);
+
+    expect(a.canonical).toBe(b.canonical);
+    expect(a.bodyHash).toBe(b.bodyHash);
+  });
+
+  it("normalizes dates and undefined values deterministically", () => {
+    const payload = {
+      createdAt: new Date("2025-01-01T00:00:00.000Z"),
+      name: "alpha",
+      skip: undefined,
+    };
+
+    const result = canonicalizePayload(payload);
+
+    expect(result.canonical).toBe(
+      '{"createdAt":"2025-01-01T00:00:00.000Z","name":"alpha"}',
+    );
+    expect(result.bodyHash).toHaveLength(64);
+  });
+});