fix: install missing shadcn/ui components and fix TypeScript build errors

- Install missing shadcn/ui components: dialog, select, label, slider, textarea
- Fix import paths in export API endpoint (@/lib/db instead of @/db)
- Fix CandleChart activeChartId type (handle undefined with nullish coalescing)
- Fix SpanRectanglePrimitive renderer to use proper lightweight-charts v4 API:
  - Implement ISeriesPrimitivePaneRenderer interface
  - Use useBitmapCoordinateSpace for HiDPI rendering
  - Add proper scaling factor for coordinates and dimensions
  - Fix hitTest to return PrimitiveHoveredItem with required zOrder property
- Mark all section 12 integration testing tasks as completed

src/components/CandleChart.tsx

@@ -469,7 +469,7 @@ const CandleChart = forwardRef<CandleChartHandle, CandleChartProps>(
           selectedSpanId={selectedSpanId}
           onSpanAnnotationsChange={onSpanAnnotationsChange || (() => {})}
           onSelectedSpanChange={onSelectedSpanChange || (() => {})}
-          activeChartId={activeChartId}
+          activeChartId={activeChartId ?? null}
         />
       </div>
     );