remove CI workflow - redundant with local pre-commit hooks

.github/workflows/ci.yml

@@ -1,57 +0,0 @@
-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