feat: Initialize backend with NestJS framework and serial communication

- Added package.json for backend dependencies and scripts.
- Implemented basic AppController and AppService with a simple "Hello World!" endpoint.
- Created SerialModule for handling serial communication with the Pico.
- Developed SerialController and SerialService to manage serial ports and commands.
- Implemented event streaming for serial data.
- Added Jest tests for AppController and e2e tests for the application.
- Set up TypeScript configuration for the backend.
- Created frontend SendBox component for sending commands to the backend.
- Established Pico firmware for controlling a stepper motor via serial commands.
- Documented project structure and usage in README files.

backend/.gitignore

@@ -0,0 +1,56 @@
+# compiled output
+/dist
+/node_modules
+/build
+
+# Logs
+logs
+*.log
+npm-debug.log*
+pnpm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+
+# OS
+.DS_Store
+
+# Tests
+/coverage
+/.nyc_output
+
+# IDEs and editors
+/.idea
+.project
+.classpath
+.c9/
+*.launch
+.settings/
+*.sublime-workspace
+
+# IDE - VSCode
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+
+# dotenv environment variable files
+.env
+.env.development.local
+.env.test.local
+.env.production.local
+.env.local
+
+# temp directory
+.temp
+.tmp
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Diagnostic reports (https://nodejs.org/api/report.html)
+report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json