tracking: add onceLoaded callback

src/lib/tracking.svelte.ts

@@ -42,6 +42,8 @@ export class TrackingManager {
 	private _consent: boolean | null = $state(null);
 	private _services: Record<string, InternalService<unknown>> = {};
 	private _changeCallbacks: Array<(consent: boolean | null) => void> = [];
+	private _loadCallbacks: Array<(consent: boolean | null) => void> = [];
+	private _loaded: boolean = false;
 	private _consentQueue: Array<() => void> = [];
 
 	/**
@@ -80,6 +82,12 @@ export class TrackingManager {
 			log.debug('[TrackingManager] Loaded tracking options from storage:', opts);
 		}
 
+		// Run load callbacks
+		this._loadCallbacks.forEach((cb) => {
+			cb(this._consent);
+		});
+		this._loaded = true;
+
 		return this;
 	}
 
@@ -152,6 +160,16 @@ export class TrackingManager {
 		this.saveOpts();
 	}
 
+	/**
+	 * Registers a callback to be called only once the tracking state has been
+	 * loaded from localStorage. Will be called immediately if already loaded
+	 * and with each subsequent load.
+	 */
+	onceLoaded(callback: (consent: boolean | null) => void) {
+		this._loadCallbacks.push(callback);
+		if (this._loaded) callback(this.consent);
+	}
+
 	/**
 	 * Registers a callback to be notified when the tracking permission changes.
 	 */