feat(ui): add dynamic sun/moon icons in theme toggle button

apps/web/src/components/theme-toggle.tsx

@@ -1,25 +1,43 @@
-"use client";
-
-import { Button } from "./ui/button";
-import { Sun, Moon } from "lucide-react";
-import { useTheme } from "next-themes";
-
-interface ThemeToggleProps {
-  className?: string;
-}
-
-export function ThemeToggle({ className }: ThemeToggleProps) {
-  const { theme, setTheme } = useTheme();
-
-  return (
-    <Button
-      size="icon"
-      variant="text"
-      className="h-7"
-      onClick={() => setTheme(theme === "dark" ? "light" : "dark")}
-    >
-      <Sun className="!size-[1.1rem]" />
-      <span className="sr-only">{theme === "dark" ? "Light" : "Dark"}</span>
-    </Button>
-  );
-}
+"use client";
+
+import { useState, useEffect } from "react";
+import { Button } from "./ui/button";
+import { Sun, Moon } from "lucide-react";
+import { useTheme } from "next-themes";
+
+interface ThemeToggleProps {
+  className?: string;
+}
+
+export function ThemeToggle({ className }: ThemeToggleProps) {
+  const { resolvedTheme, setTheme } = useTheme();
+  const [mounted, setMounted] = useState(false);
+
+  useEffect(() => setMounted(true), []);
+
+  if (!mounted) {
+    return null; // prevents hydration mismatch
+  }
+
+  const isDark = resolvedTheme === "dark";
+
+  return (
+    <Button
+      size="icon"
+      variant="text"
+      className={`h-7 ${className ?? ""}`}
+      type="button"
+      onClick={() => setTheme(isDark ? "light" : "dark")}
+      aria-pressed={!isDark}
+    >
+      {isDark ? (
+        <Moon className="!size-[1.1rem]" aria-hidden="true" />
+      ) : (
+        <Sun className="!size-[1.1rem]" aria-hidden="true" />
+      )}
+      <span className="sr-only">
+        Switch to {isDark ? "light" : "dark"} mode
+      </span>
+    </Button>
+  );
+}