feat(cli): rework build / test environment handling

.github/workflows/ci.yaml

@@ -141,6 +141,10 @@ jobs:
       contents: read
       # Push of the pre-built CI image is additionally gated to main below.
       packages: write
+    env:
+      # Registry and Environment Host roots together, so the cached build
+      # tree stays registered under the same Environment id.
+      DEBMAGIC_DATA_DIR: /tmp/debmagic-data
     steps:
       - uses: actions/checkout@v5
       - uses: Swatinem/rust-cache@v2
@@ -149,16 +153,18 @@ jobs:
       - name: Cache the debmagic build tree
         uses: actions/cache@v4
         with:
-          path: /tmp/debmagic
-          key: debmagic-build-${{ hashFiles('Cargo.lock', 'debian/changelog', 'debian/control', 'debian/rules') }}
-          restore-keys: debmagic-build-
-      - name: Prune stale build trees from the restored cache
+          path: /tmp/debmagic-data
+          key: debmagic-data-${{ hashFiles('Cargo.lock', 'debian/changelog', 'debian/control', 'debian/rules') }}
+          restore-keys: debmagic-data-
+      - name: Prune Environments of other package versions from the restored cache
         run: |
-          mkdir -p /tmp/debmagic
           current="$(dpkg-parsechangelog -SSource)-$(dpkg-parsechangelog -SVersion)"
-          find /tmp/debmagic -mindepth 1 -maxdepth 1 -type d \
-            ! -name "$current" ! -name "${current}-test" \
-            -exec rm -rf {} +
+          cargo run --locked -q -p debmagic -- env list \
+            | awk -v current="$current" 'NR > 1 && $4 != current { print $1 }' \
+            | while read -r id; do
+                cargo run --locked -q -p debmagic -- env clean "$id" \
+                  || echo "::warning::could not prune Environment $id"
+              done
       - name: Resolve CI image tag
         id: image
         run: |