fix: Update Rust edition and fix frontend TypeScript error

Dockerfile

@@ -15,7 +15,7 @@ RUN npm run build
 # ---------------------------
 # Stage 2: Build Backend (Rust)
 # ---------------------------
-FROM rust:1.75-bookworm AS backend-builder
+FROM rust:1.85-bookworm AS backend-builder
 WORKDIR /app/backend
 
 COPY backend-rust/Cargo.toml ./

backend-rust/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "backend-rust"
 version = "0.1.0"
-edition = "2024"
+edition = "2021"
 
 [dependencies]
 axum = "0.8.8"

frontend-vite/src/components/PlayerBar.tsx

@@ -461,7 +461,7 @@ export default function PlayerBar() {
                             className="w-full h-1 bg-[#4d4d4d] rounded-lg appearance-none cursor-pointer accent-white group-hover:accent-green-500"
                         />
                     </div>
-                    <button onClick={() => setIsCoverModalOpen(true)} title="Full Screen" className="text-zinc-400 hover:text-white">
+                    <button onClick={() => setIsFullScreenOpen(true)} title="Full Screen" className="text-zinc-400 hover:text-white">
                         <Maximize2 className="w-4 h-4" />
                     </button>
                 </div>