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/keymap_setup/actions.rs

@@ -164,6 +164,12 @@ pub(super) const KEYMAP_ACTIONS: &[KeymapActionDescriptor] = &[
     action("pager", "Pager", "close_transcript", "Close the transcript overlay."),
     action("list", "List", "move_up", "Move list selection up."),
     action("list", "List", "move_down", "Move list selection down."),
+    action("list", "List", "move_left", "Move horizontally left in list pickers."),
+    action("list", "List", "move_right", "Move horizontally right in list pickers."),
+    action("list", "List", "page_up", "Move list selection up by one page."),
+    action("list", "List", "page_down", "Move list selection down by one page."),
+    action("list", "List", "jump_top", "Jump to the first list item."),
+    action("list", "List", "jump_bottom", "Jump to the last list item."),
     action("list", "List", "accept", "Accept the current list selection."),
     action("list", "List", "cancel", "Cancel and close selection views."),
     action("approval", "Approval", "open_fullscreen", "Open approval details fullscreen."),
@@ -286,6 +292,12 @@ pub(super) fn binding_slot<'a>(
         ("pager", "close_transcript") => Some(&mut keymap.pager.close_transcript),
         ("list", "move_up") => Some(&mut keymap.list.move_up),
         ("list", "move_down") => Some(&mut keymap.list.move_down),
+        ("list", "move_left") => Some(&mut keymap.list.move_left),
+        ("list", "move_right") => Some(&mut keymap.list.move_right),
+        ("list", "page_up") => Some(&mut keymap.list.page_up),
+        ("list", "page_down") => Some(&mut keymap.list.page_down),
+        ("list", "jump_top") => Some(&mut keymap.list.jump_top),
+        ("list", "jump_bottom") => Some(&mut keymap.list.jump_bottom),
         ("list", "accept") => Some(&mut keymap.list.accept),
         ("list", "cancel") => Some(&mut keymap.list.cancel),
         ("approval", "open_fullscreen") => Some(&mut keymap.approval.open_fullscreen),
@@ -390,6 +402,12 @@ pub(super) fn bindings_for_action<'a>(
         ("pager", "close_transcript") => Some(runtime_keymap.pager.close_transcript.as_slice()),
         ("list", "move_up") => Some(runtime_keymap.list.move_up.as_slice()),
         ("list", "move_down") => Some(runtime_keymap.list.move_down.as_slice()),
+        ("list", "move_left") => Some(runtime_keymap.list.move_left.as_slice()),
+        ("list", "move_right") => Some(runtime_keymap.list.move_right.as_slice()),
+        ("list", "page_up") => Some(runtime_keymap.list.page_up.as_slice()),
+        ("list", "page_down") => Some(runtime_keymap.list.page_down.as_slice()),
+        ("list", "jump_top") => Some(runtime_keymap.list.jump_top.as_slice()),
+        ("list", "jump_bottom") => Some(runtime_keymap.list.jump_bottom.as_slice()),
         ("list", "accept") => Some(runtime_keymap.list.accept.as_slice()),
         ("list", "cancel") => Some(runtime_keymap.list.cancel.as_slice()),
         ("approval", "open_fullscreen") => Some(runtime_keymap.approval.open_fullscreen.as_slice()),