Persist media uploads outside public/ to survive rebuilds and redeploys

Move media storage from public/assets/images/media to storage/media
(outside Git and public/), so uploaded images, favicons and logos are
preserved across rebuilds and git clean. Add a shared media-storage helper,
update the upload/serve actions and API routes, and gitignore storage/.

src/actions/save-favicon.ts

@@ -5,8 +5,9 @@ import path from "node:path";
 import { revalidatePath } from "next/cache";
 import { prisma } from "@/lib/prisma";
 import { siteSettings } from "@/lib/services/site-settings";
+import { resolveMediaPath } from "@/lib/media-storage";
 
-const FAVICON_DIR = "public/assets/images/media/favicon";
+const FAVICON_DIR = resolveMediaPath("favicon");
 const MAX_SIZE = 2 * 1024 * 1024; // 2MB
 const ALLOWED = [
 	"image/png",
@@ -42,7 +43,7 @@ export async function saveFavicon(
 		};
 		const ext = mimeExt[file.type] ?? "png";
 		const filename = `favicon-${Date.now()}.${ext}`;
-		const baseDir = path.resolve(process.cwd(), FAVICON_DIR);
+		const baseDir = FAVICON_DIR;
 		const filePath = path.resolve(baseDir, filename);
 		if (!filePath.startsWith(baseDir + path.sep)) {
 			return { success: false, error: "Invalid path" };
@@ -99,7 +100,7 @@ export async function deleteFavicon(): Promise<{
 	try {
 		const oldUrl = await siteSettings.get("cms_favicon");
 		if (oldUrl?.startsWith("/api/media/favicon/")) {
-			const baseDir = path.resolve(process.cwd(), FAVICON_DIR);
+			const baseDir = FAVICON_DIR;
 			const oldName = oldUrl.replace("/api/media/favicon/", "");
 			if (!oldName.includes("..") && !oldName.includes("/")) {
 				const oldPath = path.resolve(baseDir, oldName);