Add KiCad files and USB CDC logging support

kicad/.gitignore

@@ -0,0 +1,24 @@
+# Temporary and local KiCad artifacts
+*-backups/
+*.kicad_prl
+*.kicad_pro-bak
+*.kicad_sch-bak
+*.kicad_pcb-bak
+*.sch-bak
+*.pcb-bak
+*.bak
+
+# Cache and automatically generated tables
+sym-lib-table-bak
+fp-lib-table-bak
+*-cache.lib
+*-cache.dcm
+
+# Generated fabrication outputs (regenerate as needed)
+*.net
+*.xml
+*.csv
+*.tsv
+*.pos
+*.ipr
+*.rpt