refactor: Implement reactive chart rendering and cleanup using Svelte's $effect on the analytics page.

src/routes/analytics/+page.svelte

@@ -1,5 +1,4 @@
 <script lang="ts">
-	import { onMount } from "svelte";
 	import { goto } from "$app/navigation";
 	import Chart from "chart.js/auto";
 	import Card from "$lib/components/ui/Card.svelte";
@@ -9,10 +8,15 @@
 	let { data } = $props();
 	let analytics = $derived(data.analytics);
 
+	// svelte-ignore non_reactive_update
 	let timelineCanvas: HTMLCanvasElement;
+	// svelte-ignore non_reactive_update
 	let pieCanvas: HTMLCanvasElement;
+	// svelte-ignore non_reactive_update
 	let electricityCanvas: HTMLCanvasElement;
+	// svelte-ignore non_reactive_update
 	let costCanvas: HTMLCanvasElement;
+	// svelte-ignore non_reactive_update
 	let printerCanvas: HTMLCanvasElement;
 
 	// Time range options
@@ -23,10 +27,9 @@
 		{ value: "365", label: "1 Year" },
 		{ value: "all", label: "All Time" },
 	];
-	let selectedRange = $state(analytics.range);
+	let selectedRange = $derived(analytics.range);
 
 	function changeRange(range: string) {
-		selectedRange = range;
 		goto(`/analytics?range=${range}`);
 	}
 
@@ -49,7 +52,21 @@
 		return parseFloat((bytes / Math.pow(k, i)).toFixed(1)) + " " + sizes[i];
 	}
 
-	onMount(() => {
+	// Chart instances
+	let timelineChart: Chart | null = null;
+	let pieChart: Chart | null = null;
+	let electricityChart: Chart | null = null;
+	let costChart: Chart | null = null;
+	let printerChart: Chart | null = null;
+
+	$effect(() => {
+		// Cleanup previous charts
+		if (timelineChart) timelineChart.destroy();
+		if (pieChart) pieChart.destroy();
+		if (electricityChart) electricityChart.destroy();
+		if (costChart) costChart.destroy();
+		if (printerChart) printerChart.destroy();
+
 		const chartColors = [
 			"#3b82f6",
 			"#8b5cf6",
@@ -60,10 +77,11 @@
 		];
 
 		// 1. Timeline Chart - Filament Usage
+		if (timelineCanvas) {
 			const dates = Object.keys(analytics.usageByDate).slice(-30);
 			const weights = dates.map((d) => analytics.usageByDate[d]);
 
-		new Chart(timelineCanvas, {
+			timelineChart = new Chart(timelineCanvas, {
 				type: "line",
 				data: {
 					labels: dates.map((d) =>
@@ -101,12 +119,14 @@
 					},
 				},
 			});
+		}
 
 		// 2. Material Pie Chart
+		if (pieCanvas) {
 			const materials = Object.keys(analytics.materialUsage);
 			const matWeights = materials.map((m) => analytics.materialUsage[m]);
 
-		new Chart(pieCanvas, {
+			pieChart = new Chart(pieCanvas, {
 				type: "doughnut",
 				data: {
 					labels: materials,
@@ -122,20 +142,25 @@
 					responsive: true,
 					maintainAspectRatio: false,
 					plugins: {
-					legend: { position: "right", labels: { color: "#94a3b8" } },
+						legend: {
+							position: "right",
+							labels: { color: "#94a3b8" },
+						},
 					},
 				},
 			});
+		}
 
 		// 3. Electricity Usage Chart
-		const electricDates = Object.keys(analytics.electricityByDate).slice(
-			-30,
-		);
+		if (electricityCanvas) {
+			const electricDates = Object.keys(
+				analytics.electricityByDate,
+			).slice(-30);
 			const electricityWh = electricDates.map(
 				(d) => analytics.electricityByDate[d] / 1000,
 			);
 
-		new Chart(electricityCanvas, {
+			electricityChart = new Chart(electricityCanvas, {
 				type: "bar",
 				data: {
 					labels: electricDates.map((d) =>
@@ -165,7 +190,11 @@
 						y: {
 							grid: { color: "rgba(255,255,255,0.1)" },
 							ticks: { color: "#94a3b8" },
-						title: { display: true, text: "kWh", color: "#94a3b8" },
+							title: {
+								display: true,
+								text: "kWh",
+								color: "#94a3b8",
+							},
 						},
 						x: {
 							grid: { display: false },
@@ -174,12 +203,14 @@
 					},
 				},
 			});
+		}
 
 		// 4. Cost Chart
+		if (costCanvas) {
 			const costDates = Object.keys(analytics.costByDate).slice(-30);
 			const costs = costDates.map((d) => analytics.costByDate[d]);
 
-		new Chart(costCanvas, {
+			costChart = new Chart(costCanvas, {
 				type: "line",
 				data: {
 					labels: costDates.map((d) =>
@@ -220,10 +251,11 @@
 					},
 				},
 			});
+		}
 
 		// 5. Printer Usage Chart
-		if (analytics.printerStats.length > 0) {
-			new Chart(printerCanvas, {
+		if (printerCanvas && analytics.printerStats.length > 0) {
+			printerChart = new Chart(printerCanvas, {
 				type: "bar",
 				data: {
 					labels: analytics.printerStats.map(
@@ -620,9 +652,7 @@
 					<p class="text-2xl font-bold text-purple-400">
 						{formatBytes(analytics.totalModelSize)}
 					</p>
-					<p class="text-xs text-slate-400 uppercase">
-						Storage Used
-					</p>
+					<p class="text-xs text-slate-400 uppercase">Storage Used</p>
 				</div>
 			</div>
 			{#if analytics.topModels.length > 0}