add cache for build

.github/workflows/android.yaml

@@ -14,10 +14,47 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v6
 
+      - name: Cache Nix store/cache
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cache/nix
+            ~/.nix-profile
+            ~/.local/share/nix
+          key: ${{ runner.os }}-nix-${{ hashFiles('flake.lock','flake.nix') }}
+          restore-keys: |
+            ${{ runner.os }}-nix-
+
+      - name: Cache Flutter Pub
+        uses: actions/cache@v4
+        with:
+          path: ~/.pub-cache
+          key: ${{ runner.os }}-pub-${{ hashFiles('pubspec.lock','pubspec.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pub-
+
+      - name: Cache Gradle
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+            android/.gradle
+          key: ${{ runner.os }}-gradle-${{ hashFiles('android/gradle.properties','android/gradle/wrapper/gradle-wrapper.properties') }}
+          restore-keys: |
+            ${{ runner.os }}-gradle-
+
       - name: Prepare Nix devshell
         uses: ./.github/actions/nix-devshell
         with:
           prebuild: "true"
+          cachix_cache: ${{ secrets.CACHIX_CACHE }}
+          cachix_auth: ${{ secrets.CACHIX_AUTH_TOKEN }}
+
+      - name: Restore Dart packages
+        uses: ./.github/actions/nix-devshell
+        with:
+          commands: flutter pub get
 
       - name: Collect Translation Files
         uses: ./.github/actions/nix-devshell