PHLEGM v6 GUI Font Toggle - 2026-10-03

Adds an always-visible GUI font-mode toggle beside the Tree/Icons view toggle.

Modes:
  Font: Former  - pre-CHR native Windows GUI font/control renderer (default).
  Font: CHR     - current Packard Bell CHR renderer (opt-in).

The former-font status and history panes are parallel native STATIC/EDIT controls
matching the pre-CHR GUI path. While Former is selected, CHR status/history
redraw scheduling is bypassed. Owner-drawn GUI labels use DEFAULT_GUI_FONT.
Raw-byte CHR data visualization remains CHR by design because it is data, not
GUI typography. The emulated-machine FPS overlay is unchanged.

Switching modes rebases the emulation timing anchor after synchronous host GUI
work so the act of toggling cannot create catch-up debt.
