remove echarts, use canvas

src/lib/charts/index.ts

@@ -0,0 +1,15 @@
+/**
+ * Canvas Charts — Barrel Export
+ *
+ * Usage:
+ *   import { CanvasChart, buildDaylightBands, SERIES_COLORS } from '$lib/charts';
+ */
+
+export { default as CanvasChart } from './CanvasChart.svelte';
+export type { ChartSeries } from './CanvasChart.svelte';
+
+export { buildDaylightBands } from './bands';
+export type { DaylightBand } from './bands';
+
+export { CHART_COLORS, SERIES_COLORS, calculateAverage, findUnit, isColumnUnit } from './data';
+export type { AverageResult } from './data';