Show tab queue hint in footer (#9138)

- show the Tab queue hint in the footer when a task is running with
Steer enabled
- drop the history queue hint and add footer snapshots

codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__chatwidget_exec_and_status_layout_vt100_snapshot.snap

@@ -2,6 +2,33 @@
 source: tui/src/chatwidget/tests.rs
 expression: term.backend().vt100().screen().contents()
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 • I’m going to search the repo for where “Change Approved” is rendered to update
   that view.
 
@@ -14,4 +41,4 @@ expression: term.backend().vt100().screen().contents()
 
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-  100% context left
+  100% context left · tab to queue message