Cards drop to a 178px grid (dialog 840px) with tighter type so more
starters fit per row; the Blank card's plus glyph goes accent-blue at
64px. Arduino Mega (mega-blink) joins the Arduino section next to the
Uno. Recaptured xiao-rp2040-blink.webp now that the board art is
silk-screened "XIAO-RP2040" (was "XIAO-ESP32-C3").
The starter cards now carry the same circuit thumbnails the examples
gallery uses (ExampleThumbnail → /examples-thumbs/<id>.webp with the
CircuitPreview SVG fallback): boards with a Blink example reuse its thumb,
the rest get freshly captured starter-<kind>.webp shots in the same folder
(XIAO S3/C3, Netduino 2, Pi 4/5; plus the missing xiao-esp32c6-blink and
xiao-rp2040-blink example thumbs).
The ESP32 section is now one card per chip generation with the Seeed XIAO
variant preferred (DevKit V1 / XIAO S3 / XIAO C3 / XIAO C6), and XIAO
RP2040 joins the Raspberry Pi section — replacing the previous
every-variant list and the separate XIAO section.
Fixes: a pristine /editor visit clears the hardcoded Uno starter BEFORE
showing the dialog (empty canvas behind; cancel now leaves a blank
workspace), and clearing the last board re-points the editor at a
nonexistent group so Monaco no longer keeps showing the deleted board's
sketch (removeBoard only re-points when another board remains).
David Montero Crespo