🔒 fix: Command Injection vulnerability in install-manager.ts

- Changed `shell: true` to `shell: false` in `spawn` calls within `electron/main/backend/install-manager.ts`.
- Updated `AGENTS.md` documentation to reflect the security best practice.
- Verified that the fix prevents command injection using a reproduction script.

Co-authored-by: vmomenv <51269338+vmomenv@users.noreply.github.com>

AGENTS.md

@@ -285,7 +285,7 @@ const execParams =
 
 // 生成进程
 const child = spawn(execCommand, execParams, {
-  shell: true,
+  shell: false,
   env: process.env,
 });