Add README documentation for HikeMap project

Created comprehensive README with features, setup instructions, and technical details.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

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+# HikeMap - KML Track Editor
+
+A single-page web application for viewing, editing, and navigating KML/GPS tracks on an interactive map.
+
+## Features
+
+### Track Editing
+- Draw new tracks directly on the map
+- Reshape existing tracks with rope physics simulation
+- Smooth tracks with a brush tool
+- Smart track snapping at endpoints with auto-splitting
+- Multi-track selection and merge operations
+- 20-step undo/redo history
+
+### Navigation Mode
+- Graph-based pathfinding using Dijkstra's algorithm
+- Automatic trail intersection detection (within 5 meters)
+- Real-time route recalculation when deviating >50m from path
+- Map rotation to face direction of travel
+- Auto-center on GPS position (toggleable)
+- Persistent destination storage
+
+### GPS Integration
+- Real-time location tracking using device GPS
+- Automatic position updates every 3 seconds
+- Requires HTTPS or localhost for geolocation API
+
+## Quick Start
+
+### Local Development
+```bash
+# Serve via HTTP (required for GPS geolocation API)
+python -m http.server 8000
+```
+Then open http://localhost:8000
+
+### Docker Deployment
+```bash
+# Build and run with Docker Compose
+docker-compose up
+```
+Access at http://localhost:8080
+
+## Technical Details
+
+### Architecture
+- **Single-file application**: Everything contained in `index.html`
+- **No build process required**: Pure HTML/CSS/JavaScript
+- **CDN dependencies**: Leaflet.js 1.9.4, leaflet-rotate 0.2.8
+
+### File Structure
+The entire application is in `index.html`:
+- Lines 1-325: CSS styles
+- Lines 326-420: HTML structure
+- Lines 421-end: JavaScript application code
+
+### Data Format
+- Supports standard KML files with Placemark elements
+- Automatically loads `default.kml` on startup if present
+- Exports edited tracks back to KML format
+
+## Browser Requirements
+- Modern browser with ES6 support
+- HTTPS connection or localhost for GPS features
+- Location services permission for navigation mode
+
+## License
+[Add your license information here]