Initial release: ESP32-C3 CO2 & environment sensor board

KiCad 10 design (schematic, 2-layer layout, custom symbols and footprints),
fabrication data for PCBWay (Gerber X2, Excellon, job file), BOM, generated
documentation (schematic PDF, layer plots, 3D render) and firmware notes.

.gitignore

@@ -0,0 +1,15 @@
+# KiCad local history and backups (local only, not part of the design)
+.history/
+_restore_backup_*/
+-backups/
+*.bak
+*.kicad_prl
+
+# Generated fabrication outputs are published in gerber/ ; keep ad-hoc exports out
+*.gbr.bak
+*.drl.bak
+
+# OS / editor noise
+.DS_Store
+*~
+*.swp