refactor GitHub workflows

Currently the workflows repeat steps unnecessarily. Compute and power
may be cheap but it's not free.

.github/workflows/build.yml

@@ -0,0 +1,100 @@
+name: Build
+on:
+  push:
+  pull_request:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  shellcheck:
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Differential ShellCheck
+        id: ShellCheck
+        uses: redhat-plumbers-in-action/differential-shellcheck@v5
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Upload artifact with ShellCheck defects in SARIF format
+        uses: actions/upload-artifact@v4
+        with:
+          name: Differential ShellCheck SARIF
+          path: ${{ steps.ShellCheck.outputs.sarif }}
+
+  build:
+    strategy:
+      matrix:
+        go:
+          - oldstable
+          - stable
+          - tip
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Install Dependencies
+        run: |
+          sudo add-apt-repository ppa:cowsql/stable -y --no-update
+          sudo apt-get update
+
+          sudo apt-get install --no-install-recommends -y \
+            autoconf \
+            automake \
+            libcowsql-dev \
+            libacl1-dev \
+            libcap-dev \
+            liblxc1 \
+            liblz4-dev \
+            libsqlite3-dev \
+            libudev-dev \
+            libuv1-dev \
+            lxc-dev \
+            make \
+            pkg-config
+
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Go (${{ matrix.go }})
+        if: matrix.go != 'tip'
+        uses: actions/setup-go@v5
+        with:
+          go-version: ${{ matrix.go }}
+
+      - name: Install Go (tip)
+        if: matrix.go == 'tip'
+        run: |
+          go install golang.org/dl/gotip@latest
+          gotip download
+          ~/sdk/gotip/bin/go version
+          echo "PATH=$HOME/go/bin:$HOME/sdk/gotip/bin/:$PATH" >> $GITHUB_ENV
+
+      - name: Save Go env
+        id: go-env
+        run: go env >> $GITHUB_OUTPUT
+
+      - name: Check compatible min Go version
+        run: |
+          go mod tidy
+
+      - name: Download go dependencies
+        run: |
+          go mod download
+
+      - name: Run Incus build
+        run: |
+          make
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: incus
+          path: |
+            ./
+            ${{ steps.go-env.GOPATH }}/

.github/workflows/tests.yml

@@ -389,7 +389,7 @@ jobs:
 
       - name: Create build directory
         run: |
-            mkdir bin
+          mkdir bin
 
       - name: Build static x86_64 incus
         env: