fix(tui): copilot review on #16707 — naming, label consistency, esc priority

- Rename `removeAt` → `removeAtInPlace` and document the mutation
  contract; the old name read like a non-mutating helper.
- Hotkey table + queue header: use `Ctrl+X` / `Esc` to match the
  rest of the UI (was `⌃X` / `esc`).
- Render the queued header as a single template literal so JSX
  text-node whitespace can't sneak into the rendered line.
- Make `Esc` while editing beat the `terminal.hasSelection` clear:
  the header promises 'Esc cancel', so an active selection
  shouldn't silently consume the keystroke.

ui-tui/src/content/hotkeys.ts

@@ -23,7 +23,7 @@ export const HOTKEYS: [string, string][] = [
   [paste + '+V / /paste', 'paste text; /paste attaches clipboard image'],
   ['Tab', 'apply completion'],
   ['↑/↓', 'completions / queue edit / history'],
-  ['Ctrl+X', 'delete the queued message you’re editing (esc cancels edit)'],
+  ['Ctrl+X', 'delete the queued message you’re editing (Esc cancels edit)'],
   [action + '+A/E', 'home / end of line'],
   [action + '+Z / ' + action + '+Y', 'undo / redo input edits'],
   [action + '+W', 'delete word'],