Initial design record for the three-piece keyboard

Two mirrored halves plus a numpad that carries the USB hub. Captures the
architecture decisions and the reasoning behind them: CH32L103 with an
STM32F103 pin-compatible escape hatch, split protocol tunnelled over USB-C
SBU through the numpad, hotswap sockets bottom-side, and why crystal-less
USB was ruled out across the whole WCH catalogue.

No boards ordered, no firmware written. Layout still undesigned.

Co-Authored-By: Claude Opus 5 <[email protected]>

.gitignore

@@ -0,0 +1,22 @@
+# agent config — can contain live API tokens
+.claude/
+.codex/
+
+# KiCad
+*-backups/
+*.kicad_prl
+*.kicad_pcb-bak
+*.kicad_sch-bak
+*.net
+fp-info-cache
+\#auto_saved_files#
+*.bak
+*~
+
+# fab output
+gerbers/
+*.zip
+
+# firmware build
+build/
+.build/