Clean release snapshot

.github/workflows/nightly.yml

@@ -0,0 +1,70 @@
+name: Nightly
+
+on:
+  schedule:
+    - cron: '0 2 * * *'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  setup:
+    runs-on: ubuntu-latest
+    outputs:
+      branch: ${{ steps.branch.outputs.branch }}
+      date: ${{ steps.date.outputs.date }}
+
+    steps:
+      - name: Find active release branch
+        id: branch
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          branch=$(gh api "repos/${{ github.repository }}/git/matching-refs/heads/release/v" \
+            --jq '[.[].ref | ltrimstr("refs/heads/")] | map(ltrimstr("refs/heads/")) | .[]' \
+            | sort -V | tail -1 || true)
+          if [[ -z "$branch" ]]; then
+            branch="main"
+          fi
+          echo "branch=$branch" >> "$GITHUB_OUTPUT"
+          echo "Active branch: $branch"
+
+      - name: Get date
+        id: date
+        run: echo "date=$(date -u +%Y%m%d)" >> "$GITHUB_OUTPUT"
+
+  build-docker:
+    needs: setup
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ needs.setup.outputs.branch }}
+          persist-credentials: false
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: |
+            ghcr.io/slopsmith/slopsmith:nightly
+            ghcr.io/slopsmith/slopsmith:nightly-${{ needs.setup.outputs.date }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max