fix: 修复 CI 中 10 个测试的 Bun mock.module 跨文件污染

- thinking.test.ts: 补 envUtils.js 防御性 mock，提供 isEnvDefinedFalsy
  和 isEnvTruthy 正确实现，覆盖 6 个其他测试文件不完整 mock 导致的污染
- launchLocalVault.test.ts: 补 keychain.js 防御性 mock，强制抛
  KeychainUnavailableError 使 store 走文件回退路径，覆盖 store.test.ts
  和 keychain.test.ts 的 mock 残留

Co-Authored-By: glm-5-turbo <zai-org@claude-code-best.win>

src/services/api/openai/__tests__/thinking.test.ts

@@ -1,9 +1,27 @@
-import { describe, expect, test, beforeEach, afterEach } from 'bun:test'
+import { describe, expect, test, beforeEach, afterEach, mock } from 'bun:test'
 import {
   isOpenAIThinkingEnabled,
   buildOpenAIRequestBody,
 } from '../requestBody.js'
 
+// Re-register envUtils.js with correct isEnvDefinedFalsy and isEnvTruthy to
+// override pollution from other test files (debug-tool-call, issue,
+// break-cache, MagicDocs/prompts, SessionMemory/prompts, cacheStats) that
+// mock this module without exporting isEnvDefinedFalsy.
+mock.module('src/utils/envUtils.js', () => ({
+  isEnvTruthy: (v: string | boolean | undefined): boolean => {
+    if (!v) return false
+    if (typeof v === 'boolean') return v
+    return ['1', 'true', 'yes', 'on'].includes(v.toLowerCase().trim())
+  },
+  isEnvDefinedFalsy: (v: string | boolean | undefined): boolean => {
+    if (v === undefined) return false
+    if (typeof v === 'boolean') return !v
+    if (!v) return false
+    return ['0', 'false', 'no', 'off'].includes(v.toLowerCase().trim())
+  },
+}))
+
 describe('isOpenAIThinkingEnabled', () => {
   const originalEnv = {
     OPENAI_ENABLE_THINKING: process.env.OPENAI_ENABLE_THINKING,