feat(tui): standardize picker navigation keys (#22347)

## Why

Picker-style UI in the TUI has accumulated a mix of hardcoded navigation
keys. Some lists supported page movement, some did not; some accepted
Vim-like keys, while others only accepted arrows; and tabbed or
horizontally adjustable pickers had no shared keymap action for
left/right movement.

This PR makes picker/list navigation consistent and configurable so
users can rely on the same defaults across the TUI.

## What Changed

- Adds shared list keymap actions for:
  - vertical movement: `move_up`, `move_down`
  - horizontal movement: `move_left`, `move_right`
  - paging and jumps: `page_up`, `page_down`, `jump_top`, `jump_bottom`
- Adds defaults:
- Up/down: arrows, `Ctrl+P/N`, `Ctrl+K/J`, and plain `k/j` where text
input is not active
  - Page up/down: `PageUp/PageDown` and `Ctrl+B/F`
  - First/last: `Home/End`
  - Left/right: `Left/Right` and `Ctrl+H/L`
- Wires the shared list keymap through picker and list surfaces
including session resume, multi-select, tabbed selection lists,
settings-style lists, app-link selection, MCP elicitation,
request-user-input, and the OSS selection wizard.
- Keeps search behavior intact by reserving printable characters for
query text in searchable pickers.
- Updates keymap setup actions, config schema, snapshots, and focused
coverage for the new list actions.

## How to Test

1. Start Codex from this branch and open the session picker, for example
with an existing session history.
2. In the session list, verify that `Ctrl+J/K` moves the selection
down/up.
3. Verify that `Ctrl+F/B` pages down/up and `Home/End` jumps to the
first/last visible session.
4. Type printable search text such as `j` or `k` and confirm it updates
the query instead of navigating.
5. Focus a picker control that changes values horizontally, such as a
session picker toolbar control, and verify `Ctrl+H/L` changes the
focused value like left/right arrows.

Targeted tests run:

- `cargo test -p codex-tui keymap::tests::`
- `cargo test -p codex-tui keymap_setup::tests::`
- `cargo test -p codex-tui horizontal_list_keys`
- `cargo test -p codex-tui page_and_jump_navigation_use_list_keymap`
- `cargo test -p codex-tui ctrl_h_l_move_provider_selection`
- `cargo test -p codex-tui scroll_state::tests`
- `cargo test -p codex-tui
switching_tabs_changes_visible_items_and_clears_search`
- `cargo test -p codex-tui toggle_sort_key_reloads_with_new_sort`

Also ran `just write-config-schema`, `just fmt`, `just fix -p
codex-tui`, `just argument-comment-lint`, and `git diff --check`.

Note: `cargo test -p codex-tui` was attempted and still aborts in the
pre-existing
`tests::fork_last_filters_latest_session_by_cwd_unless_show_all` stack
overflow, which is unrelated to this branch.

codex-rs/tui/src/chatwidget.rs

@@ -1441,7 +1441,11 @@ impl ChatWidget {
     }
 
     pub(crate) fn open_app_link_view(&mut self, params: crate::bottom_pane::AppLinkViewParams) {
-        let view = crate::bottom_pane::AppLinkView::new(params, self.app_event_tx.clone());
+        let view = crate::bottom_pane::AppLinkView::new_with_keymap(
+            params,
+            self.app_event_tx.clone(),
+            self.bottom_pane.list_keymap(),
+        );
         self.bottom_pane.show_view(Box::new(view));
         self.request_redraw();
     }
@@ -1899,6 +1903,7 @@ impl ChatWidget {
             self.config.memories.use_memories,
             self.config.memories.generate_memories,
             self.app_event_tx.clone(),
+            self.bottom_pane.list_keymap(),
         );
         self.bottom_pane.show_view(Box::new(view));
     }
@@ -4981,6 +4986,7 @@ impl ChatWidget {
             self.config.tui_status_line_use_colors,
             self.status_surface_preview_data(),
             self.app_event_tx.clone(),
+            self.bottom_pane.list_keymap(),
         );
         self.bottom_pane.show_view(Box::new(view));
     }
@@ -4992,6 +4998,7 @@ impl ChatWidget {
             Some(configured_terminal_title_items.as_slice()),
             self.terminal_title_preview_data(),
             self.app_event_tx.clone(),
+            self.bottom_pane.list_keymap(),
         );
         self.bottom_pane.show_view(Box::new(view));
     }
@@ -6517,7 +6524,11 @@ impl ChatWidget {
             })
             .collect();
 
-        let view = ExperimentalFeaturesView::new(features, self.app_event_tx.clone());
+        let view = ExperimentalFeaturesView::new(
+            features,
+            self.app_event_tx.clone(),
+            self.bottom_pane.list_keymap(),
+        );
         self.bottom_pane.show_view(Box::new(view));
     }