Add initial project structure with backend and frontend setup

- Created backend structure with Go, including main application logic and API endpoints.
- Added Docker support for both development and production environments.
- Introduced frontend using Nuxt 3 with Tailwind CSS for styling.
- Included configuration files for Docker and environment variables.
- Established basic documentation for contributing, development, and deployment processes.
- Set up .gitignore and .dockerignore files to manage ignored files in the repository.

.gitignore

@@ -0,0 +1,25 @@
+# Go build
+/hnh-map
+/hnh-map.exe
+
+# Data / runtime
+grids/
+
+# Nuxt / Node (frontend-nuxt)
+frontend-nuxt/node_modules
+frontend-nuxt/.nuxt
+frontend-nuxt/.output
+
+# Old Vue 2 frontend (if present)
+frontend/node_modules
+frontend/dist
+
+# Env and logs
+.env
+.env.*
+!.env.example
+*.log
+
+# OS / IDE
+.DS_Store
+.cursor/