ci: add Makefile-driven CI with unit, integration and e2e tests

- add GitHub Actions CI workflow using Makefile targets exclusively
- run unit, integration and e2e tests via `make test`
- publish Docker image to GHCR on SemVer tags
- force-update `stable` git tag after successful release
- add integration test for seed CLI (CSV upsert behavior)
- extend Makefile with test-unit and test-integration targets

https://chatgpt.com/share/694ee54f-b814-800f-a714-e87563e538b7

.github/workflows/ci.yml

@@ -0,0 +1,91 @@
+name: CI (make tests, stable, publish)
+
+on:
+  push:
+    branches: ["**"]
+    tags: ["v*.*.*"]   # SemVer tags like v1.2.3
+  pull_request:
+
+permissions:
+  contents: write      # push/update 'stable' tag
+  packages: write      # push to GHCR
+
+env:
+  IMAGE_NAME: baudolo
+  REGISTRY: ghcr.io
+  IMAGE_REPO: ${{ github.repository }}
+
+jobs:
+  test:
+    name: make test
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Show docker info
+        run: |
+          docker version
+          docker info
+
+      - name: Run all tests via Makefile
+        run: |
+          make test
+
+      - name: Upload E2E artifacts (always)
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: e2e-artifacts
+          path: artifacts
+          if-no-files-found: ignore
+
+  stable_and_publish:
+    name: Mark stable + publish image (SemVer tags only)
+    needs: [test]
+    runs-on: ubuntu-latest
+    if: startsWith(github.ref, 'refs/tags/v')
+
+    steps:
+      - name: Checkout (full history for tags)
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Derive version from tag
+        id: ver
+        run: |
+          TAG="${GITHUB_REF#refs/tags/}"   # v1.2.3
+          echo "tag=${TAG}" >> "$GITHUB_OUTPUT"
+
+      - name: Mark 'stable' git tag (force update)
+        run: |
+          git config user.name  "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git tag -f stable "${GITHUB_SHA}"
+          git push -f origin stable
+
+      - name: Login to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build image (Makefile)
+        run: |
+          make build
+
+      - name: Tag image for registry
+        run: |
+          # local image built by Makefile is: baudolo:local
+          docker tag "${IMAGE_NAME}:local" "${REGISTRY}/${IMAGE_REPO}:${{ steps.ver.outputs.tag }}"
+          docker tag "${IMAGE_NAME}:local" "${REGISTRY}/${IMAGE_REPO}:stable"
+          docker tag "${IMAGE_NAME}:local" "${REGISTRY}/${IMAGE_REPO}:sha-${GITHUB_SHA::12}"
+
+      - name: Push image
+        run: |
+          docker push "${REGISTRY}/${IMAGE_REPO}:${{ steps.ver.outputs.tag }}"
+          docker push "${REGISTRY}/${IMAGE_REPO}:stable"
+          docker push "${REGISTRY}/${IMAGE_REPO}:sha-${GITHUB_SHA::12}"