Pressing the manage button (GPIO1) overlays a small QR code -- "SCAN TO
MANAGE" -- in the top-right corner of whatever photo is currently on
screen, linking to the server's config page, then reverts to the plain
photo after 30 seconds.
The overlay is spliced into the existing streaming fetch as chunks pass
through (frame_client.c's http_read_fn), rather than buffering the full
192,000-byte frame in RAM: only the small overlay rectangle itself
(~30KB) is ever held in memory, generated via new stride-parameterized
drawing helpers (epd_draw_*_ex in epd_draw.c) that let the existing
QR/text drawing code target an arbitrarily-sized buffer instead of a
full-frame one. epd7in3e.c is untouched -- it has no idea an overlay
exists.
Adds a "2. CONFIGURATION" step alongside WiFi setup: a second QR code
linking straight to the captive portal page (http://<ap-ip>/), for anyone
who's joined the AP but wants a one-scan shortcut to the config form
instead of relying on the captive-portal popup. The AP netif is now
created (but not started) before the display renders, since the AP's IP
is fixed at netif creation and needed for this QR before the network is
actually up.
Pulls the pixel/text drawing primitives (previously private to
qr_onboarding.c) out into epd_draw.c/.h so the upcoming status screen can
reuse them instead of duplicating.
tfaour