Add components and hooks for event theme management

Introduced the `usePresignedUpload` hook for file uploads and multiple components for event theme management, including form handling, asset uploads, and UI enhancements. These additions support creating, editing, and managing event themes effectively.

frontend/src/app/(main)/dashboard/event-themes/[id]/edit/page.tsx

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+"use client";
+
+import React, { useEffect } from "react";
+import { useParams } from "next/navigation";
+import { useEventThemes } from "@/context/event-theme-context";
+import { Card, CardContent } from "@/components/ui/card";
+import { Loader2 } from "lucide-react";
+import { EventThemeForm } from "@/components/event-themes/event-theme-form";
+
+export default function EditThemePage() {
+  const params = useParams();
+  const themeId = params.id as string;
+  const { theme, isLoadingTheme, fetchThemeById } = useEventThemes();
+
+  useEffect(() => {
+    if (themeId) {
+      fetchThemeById(themeId);
+    }
+  }, [themeId, fetchThemeById]);
+
+  if (isLoadingTheme) {
+    return (
+      <Card className="w-full flex justify-center items-center p-12">
+        <CardContent>
+          <div className="flex flex-col items-center space-y-4">
+            <Loader2 className="h-8 w-8 animate-spin text-primary" />
+            <p className="text-lg text-gray-600">Loading theme...</p>
+          </div>
+        </CardContent>
+      </Card>
+    );
+  }
+
+  if (!theme) {
+    return (
+      <Card className="w-full p-12">
+        <CardContent>
+          <div className="text-center text-red-600">
+            <h2 className="text-xl font-semibold">Theme not found</h2>
+            <p className="mt-2">
+              The theme you are trying to edit could not be found.
+            </p>
+          </div>
+        </CardContent>
+      </Card>
+    );
+  }
+
+  return (
+    <div className="container mx-auto py-6 space-y-6">
+      <h1 className="text-3xl font-bold">Edit Theme: {theme.name}</h1>
+      <p className="text-gray-600">
+        Make changes to your theme. These changes will affect all events using
+        this theme.
+      </p>
+      <EventThemeForm mode="edit" theme={theme} />
+    </div>
+  );
+}

frontend/src/app/(main)/dashboard/event-themes/new/page.tsx

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+"use client";
+
+import React from "react";
+import { EventThemeForm } from "@/components/event-themes/event-theme-form";
+
+export default function NewThemePage() {
+  return (
+    <div className="container mx-auto py-6 space-y-6">
+      <h1 className="text-3xl font-bold">Create New Theme</h1>
+      <p className="text-gray-600">
+        Create a new theme for your events. Themes control the visual appearance
+        of your invitation pages and can include colors, fonts, and images.
+      </p>
+      <EventThemeForm mode="create" />
+    </div>
+  );
+}