fix(api): requireDatabaseUrl 早失败守卫；typecheck 门禁；build 排除 test；池生命周期注释

Co-Authored-By: Claude Code <noreply@anthropic.com>

apps/api/test/db.connect.test.ts

@@ -9,4 +9,18 @@ describe('数据库连接', () => {
     const r = (await db.execute('select 1 as ok')) as any
     expect(Number(r[0].ok)).toBe(1)
   })
+
+  it('DATABASE_URL 缺失时 getDb 早失败并给出诊断信息（不静默连 localhost）', () => {
+    const savedTest = process.env.DATABASE_URL_TEST
+    const saved = process.env.DATABASE_URL
+    delete process.env.DATABASE_URL_TEST
+    delete process.env.DATABASE_URL
+    try {
+      // postgres(undefined) 会静默回退 OS 用户@localhost:5432，必须在此前置拦截
+      expect(() => getDb()).toThrow(/DATABASE_URL not set/)
+    } finally {
+      if (savedTest !== undefined) process.env.DATABASE_URL_TEST = savedTest
+      if (saved !== undefined) process.env.DATABASE_URL = saved
+    }
+  })
 })