refactor: 统一 log.ts/debug.ts 的测试 mock 为共享定义

- 新增 tests/mocks/log.ts 和 tests/mocks/debug.ts，覆盖源文件全部实际导出
- 移除旧 mock 中不存在的导出（logToFile、logEvent、getLogFilePath）
- 13 个测试文件改为使用共享 mock，避免定义分散和不一致

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/utils/__tests__/envValidation.test.ts

@@ -1,20 +1,8 @@
 import { mock, describe, expect, test } from "bun:test";
+import { debugMock } from "../../../tests/mocks/debug";
 
 // Mock debug.ts to cut bootstrap/state dependency chain
-mock.module("src/utils/debug.ts", () => ({
-  logForDebugging: () => {},
-  isDebugMode: () => false,
-  isDebugToStdErr: () => false,
-  getDebugFilePath: () => null,
-  getDebugFilter: () => null,
-  getMinDebugLogLevel: () => "debug",
-  getDebugLogPath: () => "/tmp/mock-debug.log",
-  flushDebugLogs: async () => {},
-  enableDebugLogging: () => false,
-  setHasFormattedOutput: () => {},
-  getHasFormattedOutput: () => false,
-  logAntError: () => {},
-}));
+mock.module("src/utils/debug.ts", debugMock);
 
 const { validateBoundedIntEnvVar } = await import("../envValidation");