Initial commit: MVP scaffolding for Line of Sight application

- React frontend with MapLibre integration
- Node.js Express backend with dummy API
- Docker containerization (PostgreSQL+PostGIS, backend, frontend)
- Interactive map with direction selector
- 20 mock conurbations data
- Full project structure ready for PR workflow

.gitignore

@@ -0,0 +1,41 @@
+# Dependencies
+node_modules/
+venv/
+__pycache__/
+*.pyc
+*.pyo
+
+# Environment files
+.env
+.env.local
+.env.*.local
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Build outputs
+dist/
+build/
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Docker
+*.pid
+*.seed
+
+# Testing
+coverage/
+.nyc_output/
+
+# Project specific
+.a0proj/
+tmp/