registerProBoards() lets a hosted overlay ship boards outside the OSS tree as
data-only definitions: registration patches the exported BoardKind maps
(labels / FQBN / MicroPython) so every existing read site keeps working, and
the sites a map can't cover consult the registry — canvas render (custom
element or overlay render fn), BOARD_SIZE, pin-name mapping, picker list +
descriptions + tag, ESP32 family routing, in-browser simulator construction
and firmware load (structural ProBoardSimulator contract, duck-typed PIO
attach/detach), built-in bridge sensors, and a CS-gated built-in microSD
(sdCsPin -> sd_card.cs_pin worker config). Esp32Bridge additionally gains the
esp32-c6 machine type + TX pin (public chip knowledge — the C6 compile path
already ships) and a generic sendKey() for built-in matrix keyboards.
registerProExamples() appends gallery examples at runtime; the board ONLINE
ads recompute at render so registration hides them. OSS behavior without an
overlay is unchanged — the registry is dead code, same as the other seams.
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