style: format with carp-fmt 0.1.0; add to CI gate

Author: hellerve

.github/workflows/ci.yml

@@ -31,12 +31,26 @@ jobs:
           (cd /tmp/angler && carp -b main.carp)
           sudo install -m 755 /tmp/angler/out/angler /usr/local/bin/
 
+      - name: Install carp-fmt
+        run: |
+          set -euo pipefail
+          git clone --depth 1 https://github.com/carpentry-org/carp-fmt /tmp/carp-fmt
+          (cd /tmp/carp-fmt && carp -b main.carp)
+          sudo install -m 755 /tmp/carp-fmt/out/carp-fmt /usr/local/bin/
+
       - name: Lint
         run: |
           angler $(find . -name '*.carp' \
             -not -path './out/*' \
             -not -path './docs/*' \
             -not -path './.carp-src/*')
 
+      - name: Format check
+        run: |
+          carp-fmt --check $(find . -name '*.carp' \
+            -not -path './out/*' \
+            -not -path './docs/*' \
+            -not -path './.carp-src/*')
+
       - name: Generate docs
         run: carp -x gendocs.carp