Persist local workspace side chats and add tab close controls (#60152)

## What changed

- Save side chats as attachments to their parent conversation when local workspace history supports them, and let users reopen them from the sidebar after a restart.
- Show chat names or first-prompt previews in sidebar labels, and allow saved side chats to be renamed with `/rename`.
- Add tab close buttons, middle-click closing, and the configurable `close_sidebar_tab` shortcut, defaulting to `Ctrl-X W`. Closing a saved chat keeps it available in the picker; archiving removes it from Side chats.
- Confirm actions that stop running work, discard unsent input, or lose temporary history. Delete saved TUI side chats when deleting their parent conversation.

## Testing

Add coverage for reopening saved side chats after restart, archive handling, close confirmations, and preventing close-confirmation keys from accepting a replacement approval dialog.

GitOrigin-RevId: 3d47533d007286a7354660c08df13a83dd48d5d7

codex-rs/tui/src/keymap/bindings.rs

@@ -111,6 +111,7 @@ impl KeymapActionId {
                     | "focus_sidebar_content"
                     | "focus_sidebar_tabs"
                     | "hide_pane"
+                    | "close_sidebar_tab"
                     | "focus_pane_left"
                     | "focus_pane_right"
                     | "minimize_pane_width"
@@ -319,6 +320,7 @@ define_runtime_action_bindings! {
         focus_sidebar_content,
         focus_sidebar_tabs,
         hide_pane,
+        close_sidebar_tab,
         focus_pane_left,
         focus_pane_right,
         minimize_pane_width,

codex-rs/tui/src/keymap/chords/leader_defaults.rs

@@ -47,6 +47,7 @@ pub(in crate::keymap) fn register(
         (Global, "resize_panes", Char('r'), "r"),
         (Global, "minimize_pane_width", Char(','), ","),
         (Global, "maximize_pane_width", Char('.'), "."),
+        (Global, "close_sidebar_tab", Char('w'), "w"),
         (Global, "focus_sidebar_tabs", Char('t'), "t"),
     ] {
         if remaining == 0 {