Fix/ripgrep fallback (#1273)

* fix: tmp 目录改用 os.tmpdir() + ripgrep 缺失时自动 fallback 系统 rg

1. Shell.ts / imagePaste.ts / filesystem.ts: Linux/macOS 默认 tmp 路径
   从硬编码 '/tmp' 改为 os.tmpdir()，自动适配 Termux/Android 等无 /tmp
   的环境；macOS 桌面零变化；CLAUDE_CODE_TMPDIR 仍优先级最高。

2. ripgrep.ts: builtin rg 二进制缺失时（Android/Termux、不完整安装）
   自动 fallback 到 PATH 上的系统 rg，通过 note 字段携带人读提示；
   /doctor 渲染 note；init 启动时写一行 stderr warning。

Co-Authored-By: glm-5.2 <zai-org@claude-code-best.win>

* fix: review fix — ripgrep note 文案修正 + init catch 加调试日志

- ripgrep "no ripgrep available" note 去掉无意义的 USE_BUILTIN_RIPGREP=0 建议
- init.ts ripgrep status check 的空 catch 加 logForDebugging

Co-Authored-By: glm-5.2 <zai-org@claude-code-best.win>

---------

Co-authored-by: glm-5.2 <zai-org@claude-code-best.win>

src/utils/Shell.ts

@@ -2,6 +2,7 @@ import { execFileSync, spawn } from 'child_process'
 import { constants as fsConstants, readFileSync, unlinkSync } from 'fs'
 import { type FileHandle, mkdir, open, realpath } from 'fs/promises'
 import memoize from 'lodash-es/memoize.js'
+import { tmpdir } from 'os'
 import { isAbsolute, resolve } from 'path'
 import { join as posixJoin } from 'path/posix'
 import { logEvent } from 'src/services/analytics/index.js'
@@ -200,9 +201,10 @@ export async function exec(
     .toString(16)
     .padStart(4, '0')
 
-  // Sandbox temp directory - use per-user directory name to prevent multi-user permission conflicts
+  // Sandbox temp directory - use per-user directory name to prevent multi-user permission conflicts.
+  // tmpdir() honors $TMPDIR so non-/tmp environments (Termux/Android, containers) work out of the box.
   const sandboxTmpDir = posixJoin(
-    process.env.CLAUDE_CODE_TMPDIR || '/tmp',
+    process.env.CLAUDE_CODE_TMPDIR || tmpdir(),
     getClaudeTempDirName(),
   )