feat: add @tower/config package with env validation

packages/config/jest.config.js

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+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  testMatch: ['**/*.test.ts'],
+};

packages/config/package.json

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+{
+  "name": "@tower/config",
+  "version": "0.0.1",
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "default": "./dist/index.js"
+    }
+  },
+  "scripts": {
+    "build": "tsc",
+    "dev": "tsc --watch",
+    "test": "jest"
+  },
+  "dependencies": {
+    "zod": "^3.23.0"
+  },
+  "devDependencies": {
+    "@types/jest": "^29.0.0",
+    "jest": "^29.0.0",
+    "ts-jest": "^29.0.0",
+    "typescript": "^5.7.0"
+  }
+}

packages/config/src/index.test.ts

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+import { validateEnv } from './index';
+
+const validEnv = {
+  NODE_ENV: 'development',
+  DATABASE_URL: 'postgresql://tower:tower_dev@localhost:5432/tower_dev',
+  REDIS_URL: 'redis://localhost:6379',
+  JWT_SECRET: 'a_super_secret_key_that_is_at_least_32_chars_long',
+} as unknown as NodeJS.ProcessEnv;
+
+describe('validateEnv', () => {
+  it('returns parsed config for valid env', () => {
+    const result = validateEnv(validEnv);
+    expect(result.NODE_ENV).toBe('development');
+    expect(result.API_PORT).toBe(3001);
+  });
+
+  it('applies default API_PORT of 3001 when not set', () => {
+    const result = validateEnv(validEnv);
+    expect(result.API_PORT).toBe(3001);
+  });
+
+  it('throws when DATABASE_URL is missing', () => {
+    const { DATABASE_URL, ...withoutDb } = validEnv as Record<string, string>;
+    expect(() =>
+      validateEnv(withoutDb as unknown as NodeJS.ProcessEnv),
+    ).toThrow('Invalid environment variables');
+  });
+
+  it('throws when JWT_SECRET is shorter than 32 chars', () => {
+    expect(() =>
+      validateEnv({ ...validEnv, JWT_SECRET: 'tooshort' } as unknown as NodeJS.ProcessEnv),
+    ).toThrow('Invalid environment variables');
+  });
+
+  it('throws when DATABASE_URL is not a valid URL', () => {
+    expect(() =>
+      validateEnv({ ...validEnv, DATABASE_URL: 'not-a-url' } as unknown as NodeJS.ProcessEnv),
+    ).toThrow('Invalid environment variables');
+  });
+});

packages/config/src/index.ts

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+import { z } from 'zod';
+
+const envSchema = z.object({
+  NODE_ENV: z.enum(['development', 'test', 'production']).default('development'),
+  DATABASE_URL: z.string().url(),
+  REDIS_URL: z.string().url(),
+  API_PORT: z.coerce.number().default(3001),
+  JWT_SECRET: z.string().min(32),
+  MEILI_URL: z.string().url().default('http://localhost:7700'),
+  MEILI_MASTER_KEY: z.string().default('tower_meili_dev_key'),
+  LOG_LEVEL: z.enum(['trace', 'debug', 'info', 'warn', 'error']).default('info'),
+});
+
+export type Env = z.infer<typeof envSchema>;
+
+export function validateEnv(env: NodeJS.ProcessEnv = process.env): Env {
+  const result = envSchema.safeParse(env);
+  if (!result.success) {
+    console.error('Invalid environment variables:', result.error.format());
+    throw new Error('Invalid environment variables');
+  }
+  return result.data;
+}

packages/config/tsconfig.json

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+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "outDir": "./dist",
+    "rootDir": "./src"
+  },
+  "include": ["src"]
+}