fix(build): perbaiki referensi paket zesdex-gateway di Dockerfile & default.nix

- Dockerfile & default.nix: ganti zesdex-backend -> zesdex-gateway (binary zesdex)
- flake.nix & default.nix: versi 1.13.0 -> 1.18.2 mengikuti Cargo.toml
- chore(ci): drop cargo build --release dari check job, tambah cargo fmt --check

.github/workflows/ci.yml

@@ -21,11 +21,11 @@ jobs:
         with:
           components: clippy
 
-      - name: Build workspace
-        run: cargo build --release --workspace
-
-      - name: Test workspace
-        run: cargo test --workspace
+      - name: Format check
+        run: cargo fmt --all -- --check
 
       - name: Clippy workspace
-        run: cargo clippy --workspace -- -D warnings
+        run: cargo clippy --workspace --all-targets -- -D warnings
+
+      - name: Test workspace
+        run: cargo test --workspace