Add preferences and privacy policy

src/lib/geohash.svelte.ts

@@ -1,12 +1,15 @@
 import { OwlClient, ValidationError, ApiError } from './owlClient';
 import type { ApiStationsNearestStations } from '@owlboard/owlboard-ts';
+import { prefs } from './preferences.svelte';
 
 class NearestStationsState {
 	list = $state<ApiStationsNearestStations.StationsNearestStations[]>([]);
 	currentHash = $state('');
-	loading = $state(true);
+	loading = $state(false);
 	error = $state<string | null>(null);
 
+	private watcherId: number | null = null;
+
 	private initGeoConfig: PositionOptions = {
 		enableHighAccuracy: false,
 		timeout: 500,
@@ -20,10 +23,35 @@ class NearestStationsState {
 	};
 
 	constructor() {
-		if (typeof window !== 'undefined' && 'geolocation' in navigator) {
-			this.jumpstart();
-			this.initWatcher();
+		if (typeof window === 'undefined' || !('geolocation' in navigator)) return;
+
+		$effect.root(() => {
+			$effect(() => {
+				if (prefs.current.NearToMe) {
+					this.startTracking();
+				} else {
+					this.stopTracking();
+				}
+			});
+		});
+	}
+
+	private startTracking() {
+		if (this.watcherId !== null) return; // Already tracking
+		this.loading = true;
+		this.jumpstart();
+		this.initWatcher();
+	}
+
+	private stopTracking() {
+		if (this.watcherId !== null) {
+			navigator.geolocation.clearWatch(this.watcherId);
+			this.watcherId = null;
 		}
+		this.list = [];
+		this.currentHash = '';
+		this.loading = false;
+		this.error = null;
 	}
 
 	private jumpstart() {
@@ -35,7 +63,7 @@ class NearestStationsState {
 	}
 
 	private initWatcher() {
-		navigator.geolocation.watchPosition(
+		this.watcherId = navigator.geolocation.watchPosition(
 			(pos) => this.handleUpdate(pos.coords.latitude, pos.coords.longitude),
 			(err) => this.handleError(err),
 			this.geoConfig