feat(core): plumb distinct approval ids for command approvals (#12051)

zsh fork PR stack:
- https://github.com/openai/codex/pull/12051 👈 
- https://github.com/openai/codex/pull/12052

With upcoming support for a fork of zsh that allows us to intercept
`execve` and run execpolicy checks for each subcommand as part of a
`CommandExecution`, it will be possible for there to be multiple
approval requests for a shell command like `/path/to/zsh -lc 'git status
&& rg \"TODO\" src && make test'`.

To support that, this PR introduces a new `approval_id` field across
core, protocol, and app-server so that we can associate approvals
properly for subcommands.

codex-rs/app-server/src/thread_state.rs

@@ -20,6 +20,7 @@ type PendingInterruptQueue = Vec<(
 #[derive(Default, Clone)]
 pub(crate) struct TurnSummary {
     pub(crate) file_change_started: HashSet<String>,
+    pub(crate) command_execution_started: HashSet<String>,
     pub(crate) last_error: Option<TurnError>,
 }