feat: implement backend API for Pantree Phase 1 MVP

- Project setup: package.json, tsconfig.json, jest.config.js, .env.example
- Config: env.ts, constants.ts (ALLOWED_UNITS, bcrypt rounds, JWT, deletion windows)
- DB: Knex connection, knexfile, migrations 001-006 (users, password_reset_tokens,
  pantry_items, recipes+recipe_ingredients, shopping_lists+items, deleted_records)
- Seeds: 10 seeded recipes with full ingredient lists
- Middleware: JWT authMiddleware (validates token + user existence), errorHandler
- Utils: Pino logger, JWT sign helper, Zod validators for all request shapes
- Services: authService (signup/signin/google/pwd-reset/soft-delete/restore),
  pantryService (CRUD + case-insensitive duplicate guard),
  recipeService (browse+filter+scale), shoppingListService (CRUD+merge logic),
  syncService (delta sync + tombstone cleanup), emailService (SendGrid)
- Routes: /v1/auth, /v1/pantry, /v1/recipes, /v1/shopping-lists, /v1/sync
- App: Express factory (createApp), server entry point
- Jobs: node-cron daily hard-delete + tombstone cleanup
- Tests: validators, utils, auth, pantry, recipes, shopping lists, sync

src/test/utils.test.ts

@@ -0,0 +1,27 @@
+import { createError } from '../../middleware/errorHandler';
+import { signToken } from '../../utils/jwt';
+import jwt from 'jsonwebtoken';
+
+describe('createError', () => {
+  it('creates an error with statusCode and code', () => {
+    const err = createError('Something went wrong', 404, 'NOT_FOUND');
+    expect(err.message).toBe('Something went wrong');
+    expect(err.statusCode).toBe(404);
+    expect(err.code).toBe('NOT_FOUND');
+  });
+});
+
+describe('signToken', () => {
+  it('returns a token and expiry date', () => {
+    const { token, expiresAt } = signToken('test-user-id');
+    expect(typeof token).toBe('string');
+    expect(expiresAt).toBeInstanceOf(Date);
+    expect(expiresAt.getTime()).toBeGreaterThan(Date.now());
+  });
+
+  it('encodes userId in the token', () => {
+    const { token } = signToken('my-user-id');
+    const decoded = jwt.decode(token) as { userId: string };
+    expect(decoded.userId).toBe('my-user-id');
+  });
+});