chore(frontend): add @types/geojson dependency

Add GeoJSON type definitions for TypeScript support.

- Add @types/geojson package dependency
- Add 'geojson' to tsconfig types array

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

frontend/tsconfig.json

@@ -9,7 +9,8 @@
 		"skipLibCheck": true,
 		"sourceMap": true,
 		"strict": true,
-		"moduleResolution": "bundler"
+		"moduleResolution": "bundler",
+		"types": ["geojson"]
 	}
 	// Path aliases are handled by https://svelte.dev/docs/kit/configuration#alias
 	// except $lib which is handled by https://svelte.dev/docs/kit/configuration#files