refactor: 代码审查修复 — 错误边界、DRY抽取、测试修复、合规性改进

- P1: server.ts 统一错误边界 (withErrorHandler + AppError)，修复 3 个失败/卡死测试
- P2: db 层 wrap/paginateQuery 抽取，前端 handleResponse 抽取，parseIdFromUrl 抽取
- P3: middleware 验证消息中文化，Flex→Space 替换
- P0: docs/development/README.md 新增已知设计决策章节
- P3-11 setup 拆分已尝试回退（@testing-library/react preload 依赖无法拆分）
- P3-13 config 层测试从本次变更移除

tests/server/bootstrap.test.ts

@@ -1,5 +1,5 @@
-/* eslint-disable @typescript-eslint/no-empty-function, @typescript-eslint/require-await */
-import { describe, expect, test } from "bun:test";
+/* eslint-disable @typescript-eslint/require-await */
+import { afterEach, describe, expect, test } from "bun:test";
 import { mkdirSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
@@ -49,6 +49,19 @@ function makeTempConfig(overrides: Partial<ResolvedConfig> = {}): ResolvedConfig
 }
 
 describe("bootstrap", () => {
+  const shutdownHandlers: Array<() => void> = [];
+
+  afterEach(() => {
+    for (const fn of shutdownHandlers) {
+      try {
+        fn();
+      } catch {
+        // exit mock throws, that's expected
+      }
+    }
+    shutdownHandlers.length = 0;
+  });
+
   test("使用默认依赖启动", async () => {
     let started = false;
     let signalRegistered = false;
@@ -56,7 +69,8 @@ describe("bootstrap", () => {
 
     const cfg = makeTempConfig();
     const mockLoadConfig = (async () => cfg) as unknown as BootstrapDependencies["loadConfig"];
-    const mockOnSignal = (_signal: string, _handler: () => void) => {
+    const mockOnSignal = (_signal: string, handler: () => void) => {
+      shutdownHandlers.push(handler);
       signalRegistered = true;
     };
     const mockStartServer = (options: StartServerOptions) => {
@@ -67,6 +81,9 @@ describe("bootstrap", () => {
 
     const deps: BootstrapDependencies = {
       createLogger: async () => createMemoryLogger(),
+      exit: (code: number) => {
+        throw new Error(`exit(${code})`);
+      },
       loadConfig: mockLoadConfig,
       onSignal: mockOnSignal,
       startServer: mockStartServer,
@@ -90,8 +107,13 @@ describe("bootstrap", () => {
         expect(version).toBe("1.2.3");
         return createMemoryLogger();
       },
+      exit: (code: number) => {
+        throw new Error(`exit(${code})`);
+      },
       loadConfig: async () => cfg,
-      onSignal: () => {},
+      onSignal: (_signal, handler) => {
+        shutdownHandlers.push(handler);
+      },
       startServer: (options: StartServerOptions) => {
         receivedVersion = options.version;
         return {};
@@ -191,7 +213,13 @@ describe("bootstrap", () => {
 
     const deps: BootstrapDependencies = {
       createLogger: async () => mockLogger,
+      exit: (code: number) => {
+        throw new Error(`exit(${code})`);
+      },
       loadConfig: async () => cfg,
+      onSignal: (_signal, handler) => {
+        shutdownHandlers.push(handler);
+      },
       startServer: () => ({}),
     };
 
@@ -202,7 +230,7 @@ describe("bootstrap", () => {
 
   test("shutdown 时 flush logger", async () => {
     let flushed = false;
-    let shutdownHandler: (() => void) | undefined;
+    let exitCode: number | undefined;
 
     const mockLogger = createMemoryLogger();
     mockLogger.flush = () => {
@@ -212,17 +240,29 @@ describe("bootstrap", () => {
     const cfg = makeTempConfig();
     const deps: BootstrapDependencies = {
       createLogger: async () => mockLogger,
+      exit: (code: number) => {
+        exitCode = code;
+        throw new Error("exit called");
+      },
       loadConfig: async () => cfg,
       onSignal: (_signal, handler) => {
-        shutdownHandler = handler;
+        shutdownHandlers.push(handler);
       },
       startServer: () => ({}),
     };
 
     await bootstrap({ configPath: join(cfg.configDir, "config.yaml"), mode: "production" }, deps);
 
-    expect(shutdownHandler).toBeDefined();
-    shutdownHandler!();
+    const handler = shutdownHandlers.pop();
+    expect(handler).toBeDefined();
+
+    try {
+      handler!();
+    } catch {
+      // expected - exit threw
+    }
+
     expect(flushed).toBe(true);
+    expect(exitCode).toBe(0);
   });
 });

tests/server/config.test.ts

@@ -224,7 +224,8 @@ describe("loadServerConfig", () => {
       await loadServerConfig(yamlPath);
       expect.unreachable();
     } catch (error) {
-      expect((error as Error).message).toContain("日志等级");
+      expect((error as Error).message).toContain("server.logging.level");
+      expect((error as Error).message).toContain("不在允许范围内");
     } finally {
       await rm(yamlPath, { force: true });
     }