feat(tui): add /statusline command for interactive status line configuration (#10546)

## Summary
- Adds a new `/statusline` command to configure TUI footer status line
- Introduces reusable `MultiSelectPicker` component with keyboard
navigation, optional ordering and toggle support
- Implement status line setup modal that persist configuration to
config.toml

  ## Status Line Items
  The following items can be displayed in the status line:
  - **Model**: Current model name (with optional reasoning level)
  - **Context**: Remaining/used context window percentage
  - **Rate Limits**: 5-day and weekly usage limits
  - **Git**: Current branch (with optimized lookups)
  - **Tokens**: Used tokens, input/output token counts
  - **Session**: Session ID (full or shortened prefix)
  - **Paths**: Current directory, project root
  - **Version**: Codex version

  ## Features
  - Live preview while configuring status line items
  - Fuzzy search filtering in the picker
  - Intelligent truncation when items don't fit
  - Items gracefully omit when data is unavailable
  - Configuration persists to `config.toml`
  - Validates and warns about invalid status line items

  ## Test plan
  - [x] Run `/statusline` and verify picker UI appears
  - [x] Toggle items on/off and verify live preview updates
  - [x] Confirm selection persists after restart
  - [x] Verify truncation behavior with many items selected
  - [x] Test git branch detection in and out of git repos

---------

Co-authored-by: Josh McKinney <joshka@openai.com>

codex-rs/tui/src/bottom_pane/mod.rs

@@ -36,11 +36,14 @@ use crossterm::event::KeyCode;
 use crossterm::event::KeyEvent;
 use ratatui::buffer::Buffer;
 use ratatui::layout::Rect;
+use ratatui::text::Line;
 use std::time::Duration;
 
 mod app_link_view;
 mod approval_overlay;
+mod multi_select_picker;
 mod request_user_input;
+mod status_line_setup;
 pub(crate) use app_link_view::AppLinkView;
 pub(crate) use approval_overlay::ApprovalOverlay;
 pub(crate) use approval_overlay::ApprovalRequest;
@@ -74,6 +77,8 @@ pub(crate) use feedback_view::feedback_selection_params;
 pub(crate) use feedback_view::feedback_upload_consent_params;
 pub(crate) use skills_toggle_view::SkillsToggleItem;
 pub(crate) use skills_toggle_view::SkillsToggleView;
+pub(crate) use status_line_setup::StatusLineItem;
+pub(crate) use status_line_setup::StatusLineSetupView;
 mod paste_burst;
 pub mod popup_consts;
 mod queued_user_messages;
@@ -862,6 +867,16 @@ impl BottomPane {
             RenderableItem::Owned(Box::new(flex2))
         }
     }
+
+    pub(crate) fn set_status_line(&mut self, status_line: Option<Line<'static>>) {
+        self.composer.set_status_line(status_line);
+        self.request_redraw();
+    }
+
+    pub(crate) fn set_status_line_enabled(&mut self, enabled: bool) {
+        self.composer.set_status_line_enabled(enabled);
+        self.request_redraw();
+    }
 }
 
 impl Renderable for BottomPane {