fix: improve dark mode compatibility and chart visibility

- Fix TopQuestionsChart with proper dark mode colors using CSS variables and shadcn/ui components
- Enhance ResponseTimeDistribution with thicker bars (maxBarSize: 60)
- Replace GeographicMap with dark/light mode compatible CartoDB tiles
- Add custom text selection background color with primary theme color
- Update all loading states to use proper CSS variables instead of hardcoded colors
- Fix dashboard layout background to use bg-background instead of bg-gray-100

components/magicui/shine-border.tsx

@@ -0,0 +1,63 @@
+"use client";
+
+import * as React from "react";
+
+import { cn } from "@/lib/utils";
+
+interface ShineBorderProps extends React.HTMLAttributes<HTMLDivElement> {
+  /**
+   * Width of the border in pixels
+   * @default 1
+   */
+  borderWidth?: number;
+  /**
+   * Duration of the animation in seconds
+   * @default 14
+   */
+  duration?: number;
+  /**
+   * Color of the border, can be a single color or an array of colors
+   * @default "#000000"
+   */
+  shineColor?: string | string[];
+}
+
+/**
+ * Shine Border
+ *
+ * An animated background border effect component with configurable properties.
+ */
+export function ShineBorder({
+  borderWidth = 1,
+  duration = 14,
+  shineColor = "#000000",
+  className,
+  style,
+  ...props
+}: ShineBorderProps) {
+  return (
+    <div
+      style={
+        {
+          "--border-width": `${borderWidth}px`,
+          "--duration": `${duration}s`,
+          backgroundImage: `radial-gradient(transparent,transparent, ${
+            Array.isArray(shineColor) ? shineColor.join(",") : shineColor
+          },transparent,transparent)`,
+          backgroundSize: "300% 300%",
+          mask: `linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0)`,
+          WebkitMask: `linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0)`,
+          WebkitMaskComposite: "xor",
+          maskComposite: "exclude",
+          padding: "var(--border-width)",
+          ...style,
+        } as React.CSSProperties
+      }
+      className={cn(
+        "pointer-events-none absolute inset-0 size-full rounded-[inherit] will-change-[background-position] motion-safe:animate-shine",
+        className,
+      )}
+      {...props}
+    />
+  );
+}