chore: tidy repo formatting and linting

.github/workflows/ci.yml

@@ -0,0 +1,57 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+      - master
+  pull_request:
+
+jobs:
+  backend:
+    name: Backend
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+      - name: Verify gofmt
+        run: |
+          fmt_out=$(gofmt -l ./cmd ./internal ./pkg)
+          if [ -n "$fmt_out" ]; then
+            echo "The following files are not gofmt formatted:"
+            echo "$fmt_out"
+            exit 1
+          fi
+      - name: Go vet
+        run: go vet ./...
+      - name: Go test
+        run: go test ./...
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v6
+        with:
+          version: latest
+          args: ./...
+
+  frontend:
+    name: Frontend
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: frontend-modern
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+          cache-dependency-path: frontend-modern/package-lock.json
+      - name: Install dependencies
+        run: npm ci
+      - name: Lint
+        run: npm run lint
+      - name: Type check
+        run: npm run type-check
+      - name: Format check
+        run: npm run format:check