fix: make test suite runnable without DB/Chrome, add tests to CI

- Refactor index.ts to skip start() when NODE_ENV=test
- Add test setup with mocks for db, keys, browser, verification, email, usage
- Add vitest.config.ts with setup file
- Rewrite tests to work with mocks (42 tests, all passing)
- Add new tests: signup 410, recovery validation, CORS headers, error format, API root
- Add test step to CI pipeline before Docker build

src/__tests__/setup.ts

@@ -0,0 +1,91 @@
+import { vi } from "vitest";
+
+// Must be set before any imports
+process.env.NODE_ENV = "test";
+process.env.API_KEYS = "test-key";
+
+// Mock database
+vi.mock("../services/db.js", () => {
+  const mockPool = {
+    connect: vi.fn().mockResolvedValue({
+      query: vi.fn().mockResolvedValue({ rows: [{ version: "PostgreSQL 17.4" }], rowCount: 0 }),
+      release: vi.fn(),
+    }),
+    query: vi.fn().mockResolvedValue({ rows: [], rowCount: 0 }),
+    end: vi.fn().mockResolvedValue(undefined),
+    on: vi.fn(),
+    totalCount: 10,
+    idleCount: 8,
+    waitingCount: 0,
+  };
+  return {
+    default: mockPool,
+    pool: mockPool,
+    initDatabase: vi.fn().mockResolvedValue(undefined),
+    queryWithRetry: vi.fn().mockResolvedValue({ rows: [], rowCount: 0 }),
+    connectWithRetry: vi.fn().mockResolvedValue({
+      query: vi.fn().mockResolvedValue({ rows: [], rowCount: 0 }),
+      release: vi.fn(),
+    }),
+    cleanupStaleData: vi.fn().mockResolvedValue({ expiredVerifications: 0, staleKeys: 0, orphanedUsage: 0 }),
+    isTransientError: vi.fn().mockReturnValue(false),
+  };
+});
+
+// Mock keys service with in-memory store
+vi.mock("../services/keys.js", () => {
+  const keys = [
+    { key: "test-key", tier: "pro" as const, email: "test@docfast.dev", createdAt: new Date().toISOString() },
+  ];
+  return {
+    loadKeys: vi.fn().mockResolvedValue(undefined),
+    isValidKey: vi.fn((k: string) => keys.some((e) => e.key === k)),
+    getKeyInfo: vi.fn((k: string) => keys.find((e) => e.key === k)),
+    isProKey: vi.fn((k: string) => keys.find((e) => e.key === k)?.tier === "pro"),
+    getAllKeys: vi.fn(() => [...keys]),
+    createFreeKey: vi.fn(),
+    createProKey: vi.fn(),
+    downgradeByCustomer: vi.fn(),
+    findKeyByCustomerId: vi.fn(),
+    updateKeyEmail: vi.fn(),
+    updateEmailByCustomer: vi.fn(),
+  };
+});
+
+// Mock browser service
+vi.mock("../services/browser.js", () => ({
+  initBrowser: vi.fn().mockResolvedValue(undefined),
+  closeBrowser: vi.fn().mockResolvedValue(undefined),
+  renderPdf: vi.fn().mockResolvedValue(Buffer.from("%PDF-1.4 mock pdf content here")),
+  renderUrlPdf: vi.fn().mockResolvedValue(Buffer.from("%PDF-1.4 mock url pdf content")),
+  getPoolStats: vi.fn().mockReturnValue({
+    poolSize: 16,
+    totalPages: 16,
+    availablePages: 14,
+    queueDepth: 0,
+    pdfCount: 0,
+    restarting: false,
+    uptimeMs: 10000,
+    browsers: [],
+  }),
+}));
+
+// Mock verification service
+vi.mock("../services/verification.js", () => ({
+  verifyToken: vi.fn().mockReturnValue({ status: "invalid" }),
+  loadVerifications: vi.fn().mockResolvedValue(undefined),
+  createPendingVerification: vi.fn().mockResolvedValue({ email: "test@test.com", code: "123456" }),
+  verifyCode: vi.fn().mockResolvedValue({ status: "ok" }),
+}));
+
+// Mock email service
+vi.mock("../services/email.js", () => ({
+  sendVerificationEmail: vi.fn().mockResolvedValue(undefined),
+}));
+
+// Mock usage middleware  
+vi.mock("../middleware/usage.js", () => ({
+  usageMiddleware: vi.fn((_req: any, _res: any, next: any) => next()),
+  loadUsageData: vi.fn().mockResolvedValue(undefined),
+  getUsageStats: vi.fn().mockReturnValue({ totalRequests: 0, keys: {} }),
+}));