feat(hardware): initial hardware documentation, 3D models, and ESP32 client code

- Add initial versions of hardware bills of materials (BOM v1-v4), shopping lists, plan, and assembly guides.
- Add STL models for 3D-printing the 1/27 scale OpenRC F1 car parts.
- Add Blender 3D project files (.blend) and camera renders of the car design iterations.
- Add ESP32 client firmware source (client.ino) for handling video streaming and car controls.
- Ignore Blender backup files (*.blend1, *.blend2) and IDE directories.

.gitignore

@@ -7,3 +7,7 @@ server/poc-server.exe
 **/__pycache__/
 *.log
 .DS_Store
+.vscode/
+.grepai/
+*.blend1
+*.blend2