Major refactor to blue-build to allow more complex builds

.github/workflows/build.yml

@@ -0,0 +1,36 @@
+name: bluebuild
+on:
+  schedule:
+    - cron: "00 07 * * *" # build at 07:00 UTC every day 
+                          # (1:20 hours after last ublue images start building)
+  push:
+    paths-ignore: # don't rebuild if only documentation has changed
+      - "**.md"
+
+  pull_request:
+  workflow_dispatch: # allow manually triggering builds
+jobs:
+  bluebuild:
+    name: Build Custom Image
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+      id-token: write
+    strategy:
+      fail-fast: false # stop GH from cancelling all matrix builds if one fails
+      matrix:
+        recipe:
+          - recipe.yml
+    steps:
+       # the build is fully handled by the reusable github action
+      - name: Build Custom Image
+        uses: blue-build/github-action@v1.7
+        with:
+          recipe: ${{ matrix.recipe }}
+          cosign_private_key: ${{ secrets.SIGNING_SECRET }}
+          registry_token: ${{ github.token }}
+          pr_event_number: ${{ github.event.number }}
+
+          # enabled by default, disable if your image is small and you want faster builds      
+          maximize_build_space: false