Automate Go testing and linting via GitHub Actions

Set up a continuous integration workflow to verify formatting, vet code,
and run tests on every push and pull request.

Author: micthiesen

.github/workflows/ci.yml

@@ -0,0 +1,28 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+
+      - name: Check formatting
+        run: test -z "$(gofmt -l .)"
+
+      - name: Vet
+        run: go vet ./...
+
+      - name: Test
+        run: go test ./...
+
+      - name: Build
+        run: go build ./...

README.md

@@ -1,5 +1,7 @@
 # shellshape
 
+[![CI](https://github.com/micthiesen/shellshape/actions/workflows/ci.yml/badge.svg)](https://github.com/micthiesen/shellshape/actions/workflows/ci.yml)
+
 Normalize shell commands into stable "shapes" for use as cache keys,
 fingerprints, or classification inputs.