Remote mode showed a black screen on 2 MB-PSRAM boards (Heltec V4): the
mirror ring/shadow were too big to allocate. Size the ring to one frame
and drop the remote render to 400x240 so the whole footprint is smaller
than VNC's (which already worked). Add a touch-and-hold (3 s) exit for
keyboard-less touch boards and an Exit button on the web page.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
