Detach non-interactive subprocesses from stdin (#34612)

## What changed

Redirect stdin to null when launching:

- `codex doctor --json` for uploaded diagnostic reports
- Git commands used by `codex doctor`
- ripgrep searches over rollout files
- the Windows sandbox setup refresh helper

This keeps these non-interactive subprocesses from reading Codex's inherited
input stream.

GitOrigin-RevId: 063d191b0b1b849d74b55a7d6ff2f0b3d5212c86

codex-rs/tui/src/tui.rs

@@ -313,7 +313,7 @@ pub(super) fn reapply_raw_mode_after_resume() -> Result<()> {
 
 /// Restore the terminal after Codex is exiting.
 ///
-/// Uses a stronger keyboard reset than [`restore`] so the parent shell recovers even if a
+/// Uses a stronger keyboard reset than `restore` so the parent shell recovers even if a
 /// terminal missed the stack pop that normally pairs with [`set_modes`].
 pub fn restore_after_exit() -> Result<()> {
     let mut first_error =