cache compiled deps

Signed-off-by: Ronni Skansing <rskansing@gmail.com>

.github/workflows/test-build.yml

@@ -52,13 +52,21 @@ jobs:
           mkdir -p backend/frontend/build
           cp -r frontend/build/* backend/frontend/build/
 
+      - name: Cache Go build cache
+        uses: actions/cache@v4
+        with:
+          path: /tmp/go-build-cache
+          key: go-build-${{ runner.os }}-${{ hashFiles('backend/go.sum') }}
+          restore-keys: go-build-${{ runner.os }}-
+
       - name: Build binaries for multiple architectures
         run: |
-          mkdir -p build/amd64 build/arm64
+          mkdir -p build/amd64 build/arm64 /tmp/go-build-cache
 
           # build amd64 binary — static musl so no glibc floor on target systems
           sudo docker run --rm \
           -v "$(pwd)":/app \
+          -v /tmp/go-build-cache:/root/.cache/go-build \
           -w /app/backend \
           golang:1.25.10-alpine \
           sh -c "apk add --no-cache gcc musl-dev && go build -trimpath \
@@ -69,6 +77,7 @@ jobs:
           sudo docker run --rm \
           --platform linux/arm64 \
           -v "$(pwd)":/app \
+          -v /tmp/go-build-cache:/root/.cache/go-build \
           -w /app/backend \
           golang:1.25.10-alpine \
           sh -c "apk add --no-cache gcc musl-dev && go build -trimpath \