fix: enhance test setup and environment configuration for improved reliability

test/helpers/setup-env.ts

@@ -0,0 +1,18 @@
+/**
+ * Test environment setup — sets default env vars BEFORE any module is loaded.
+ *
+ * This prevents `src/env.ts` from throwing at import time when required
+ * environment variables are absent.  Add this file as a `--preload` argument
+ * to `bun test` calls in package.json.
+ *
+ * Only the 5 env vars that `src/env.ts` considers required are set here.
+ * Optional vars (S3_SECRET_KEY, ADMIN_API_TOKEN, etc.) use their own
+ * defaults in `src/env.ts` and are not touched.
+ */
+
+process.env.BOT_TOKEN ||= '123456:ABC-DEF';
+process.env.STORAGE_CHANNEL_ID ||= '-1001234567890';
+process.env.BASE_URL ||= 'https://example.com';
+process.env.DATABASE_URL ||= 'postgresql://user:pass@localhost:5432/test';
+process.env.PORT ||= '3000';
+process.env.NODE_ENV = 'test';