feat: implement GeoJSON outline panel integration with map highlighting

[IanMayo]

Summary

Implements comprehensive outline panel integration for the Debrief VS Code Extension's custom GeoJSON editor with map-based feature highlighting capability.

Key Features

• Custom tree view displaying GeoJSON features in Explorer sidebar
• Real-time outline updates when switching between .plot.json files
• Click-to-highlight functionality - selecting features in outline highlights them on the Leaflet map
• Automatic map panning to highlighted features
• Visual highlighting with orange circle markers for enhanced visibility

Technical Implementation

• Custom TreeDataProvider that parses GeoJSON FeatureCollection documents
• WebView message passing system for outline-to-map communication
• Active webview panel tracking for multi-tab support
• Graceful error handling for malformed GeoJSON files

Files Modified

• src/customOutlineTreeProvider.ts - Main outline tree view implementation
• src/plotJsonEditor.ts - Enhanced custom editor with webview messaging
• src/extension.ts - Extension registration and command handling
• media/plotJsonEditor.js - Map highlighting functionality
• package.json - Tree view and command contributions

Test Plan

• Open .plot.json files and verify outline populates with feature names
• Switch between multiple .plot.json tabs and confirm outline updates
• Click on outline entries and verify map highlighting works
• Test with files containing multiple features (London, Paris, Berlin examples)
• Verify highlights clear when selecting different features
• Confirm map pans to highlighted features automatically

Research Documentation

Includes comprehensive research documentation on VS Code custom editor outline integration challenges and proven workarounds for future reference.

Resolves outline panel integration requirements with robust, production-ready implementation.

[github-actions]

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🌐 Preview URL: https://pr-5-futuredebrief.fly.dev

📋 Details:

• App Name: pr-5-futuredebrief
• Build: 9ad0a979738fa3a52fb2a896b1fda0ad1890e270
• PR: feat: implement GeoJSON outline panel integration with map highlighting #5

🔧 What's included:

• VS Code (code-server) environment
• Debrief extension pre-installed
• Sample workspace with test files

💡 How to use:

1. Click the preview URL above
2. Open any .plot.json file to test the custom editor
3. Use Ctrl+Shift+P to access extension commands
4. Check the Explorer panel for the "Hello World" view

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• PR: feat: implement GeoJSON outline panel integration with map highlighting #5

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