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/status/mod.rs

@@ -1,3 +1,11 @@
+//! Status output formatting and display adapters for the TUI.
+//!
+//! This module turns protocol-level snapshots into stable display structures used by `/status`
+//! output and footer/status-line helpers, while keeping rendering concerns out of transport-facing
+//! code.
+//!
+//! `rate_limits` is the main integration point for status-line usage-limit items: it converts raw
+//! window snapshots into local-time labels and classifies data as available, stale, or missing.
 mod account;
 mod card;
 mod format;
@@ -5,8 +13,10 @@ mod helpers;
 mod rate_limits;
 
 pub(crate) use card::new_status_output;
+pub(crate) use helpers::format_directory_display;
 pub(crate) use helpers::format_tokens_compact;
 pub(crate) use rate_limits::RateLimitSnapshotDisplay;
+pub(crate) use rate_limits::RateLimitWindowDisplay;
 pub(crate) use rate_limits::rate_limit_snapshot_display;
 
 #[cfg(test)]