Add backend-agnostic terminal color support via OSC escape sequences:
- New backend/terminal.py with palette_printf() and exec_shell_script()
shared by both Docker and smolmachines bottle backends
- Emits OSC 4 (indexed palette) + OSC 11 (default background tint)
before launching; resets both on agent exit via OSC 104/111
- OSC 11 background tint is visible even when the TUI uses true/24-bit
colors (which bypass the palette), as Codex does for its chrome
- Fix Codex [tui] config: status_line=["model-with-reasoning"],
theme="ansi" (dark-ansi and cwd/directory were invalid identifiers)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
