feat(tui): add character jump navigation (Ctrl+], Ctrl+Alt+]) (#1074)

Add Bash/Readline-style character search:

- Ctrl+] enters forward jump mode, awaits next character, jumps to it
- Ctrl+Alt+] does the same but searches backward
- Multi-line search
- Case-sensitive matching
- Pressing the hotkey again cancels; control chars cancel and fall
  through

packages/tui/README.md

@@ -298,8 +298,13 @@ editor.getPaddingX();  // Get current padding
 - `Enter` - Submit
 - `Shift+Enter`, `Ctrl+Enter`, or `Alt+Enter` - New line (terminal-dependent, Alt+Enter most reliable)
 - `Tab` - Autocomplete
-- `Ctrl+K` - Delete line
+- `Ctrl+K` - Delete to end of line
+- `Ctrl+U` - Delete to start of line
+- `Ctrl+W` or `Alt+Backspace` - Delete word backwards
+- `Alt+D` or `Alt+Delete` - Delete word forwards
 - `Ctrl+A` / `Ctrl+E` - Line start/end
+- `Ctrl+]` - Jump forward to character (awaits next keypress, then moves cursor to first occurrence)
+- `Ctrl+Alt+]` - Jump backward to character
 - Arrow keys, Backspace, Delete work as expected
 
 ### Markdown