Add Firmware and CompanionApp as submodules

Firmware -> MeadeController-Firmware (ESP32-C6 LX200 controller)
CompanionApp -> MeadeController-CompanionApp (iOS companion app)

Hardware/ (schematics/CAD) and editor-local files (.clangd, .vscode)
are left out for now, scoped to just the two software repos.

.gitignore

@@ -0,0 +1,3 @@
+build/
+.DS_Store
+.vscode/

.gitmodules

@@ -0,0 +1,6 @@
+[submodule "Firmware"]
+	path = Firmware
+	url = git@github.com:manvalan/MeadeController-Firmware.git
+[submodule "CompanionApp"]
+	path = CompanionApp
+	url = git@github.com:manvalan/MeadeController-CompanionApp.git