Improve media manager UI: search, delete, drag-and-drop, file meta

Add a richer media manager with filename search, per-file delete with
confirmation, drag-and-drop uploads, copy-URL feedback, file size/type/date
metadata, and server-side upload validation that returns errors to the UI.
Extend the /api/media listing with size and uploaded timestamps.

src/actions/admin-media.ts

@@ -10,12 +10,16 @@ import { MEDIA_ROOT, resolveMediaPath } from "@/lib/media-storage";
 const MAX_SIZE = 5 * 1024 * 1024; // 5MB
 const ALLOWED = ["image/png", "image/jpeg", "image/gif", "image/webp"];
 
-export async function uploadMedia(formData: FormData): Promise<void> {
+export async function uploadMedia(
+	formData: FormData,
+): Promise<{ ok: boolean; error?: string }> {
 	await requirePermission(PERMS.PAGES_EDIT);
 	const file = formData.get("file") as File | null;
-	if (!file || file.size === 0) return;
-	if (file.size > MAX_SIZE) return;
-	if (!ALLOWED.includes(file.type)) return;
+	if (!file || file.size === 0) return { ok: false, error: "No file provided" };
+	if (file.size > MAX_SIZE)
+		return { ok: false, error: "File too large (max 5MB)" };
+	if (!ALLOWED.includes(file.type))
+		return { ok: false, error: "Invalid file type. Allowed: PNG, JPEG, GIF, WebP" };
 
 	const baseDir = MEDIA_ROOT;
 	// eslint-disable-next-line security/detect-non-literal-fs-filename
@@ -31,6 +35,7 @@ export async function uploadMedia(formData: FormData): Promise<void> {
 
 	revalidatePath("/api/media");
 	revalidatePath("/admin/media");
+	return { ok: true };
 }
 
 export async function deleteMedia(name: string): Promise<void> {