feat: migrate to apache echarts (#4)

Co-authored-by: terraputix <terraputix@mailbox.org>
Reviewed-on: useweb/open-meteo-blue#4

src/lib/components/charts/index.ts

@@ -0,0 +1,12 @@
+/**
+ * Chart Components — Barrel Export
+ *
+ * Re-exports all chart-related Svelte components from a single entry point.
+ *
+ * Usage:
+ *   import { EChart, ChartContainer, ChartToolbar } from '$lib/components/charts';
+ */
+
+export { default as EChart } from './EChart.svelte';
+export { default as ChartContainer } from './ChartContainer.svelte';
+export { default as ChartToolbar } from './ChartToolbar.svelte';