ci 👷: add GitHub Actions workflow for linting and testing

Set up comprehensive CI pipeline with three jobs:

- Lint: Runs ESLint and type checking
- Test: Executes test suite with Coveralls integration
- Build: Verifies package builds correctly

The workflow uses pnpm and caches dependencies for faster runs.

.github/workflows/ci.yml

@@ -0,0 +1,137 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+env:
+  NODE_VERSION: '20.18.3'
+  PNPM_VERSION: '10.5.0'
+  COVERAGE_REPORT_PATH: './coverage/vitest-reports/lcov.info'
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v2
+        with:
+          version: ${{ env.PNPM_VERSION }}
+          run_install: false
+
+      - name: Get pnpm store directory
+        id: pnpm-cache
+        shell: bash
+        run: |
+          echo "STORE_PATH=$(pnpm store path)" >> $GITHUB_OUTPUT
+
+      - name: Setup pnpm cache
+        uses: actions/cache@v3
+        with:
+          path: ${{ steps.pnpm-cache.outputs.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pnpm-store-
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Build package
+        run: pnpm build
+
+  lint:
+    name: Lint
+    needs: build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v2
+        with:
+          version: ${{ env.PNPM_VERSION }}
+          run_install: false
+
+      - name: Get pnpm store directory
+        id: pnpm-cache
+        shell: bash
+        run: |
+          echo "STORE_PATH=$(pnpm store path)" >> $GITHUB_OUTPUT
+
+      - name: Setup pnpm cache
+        uses: actions/cache@v3
+        with:
+          path: ${{ steps.pnpm-cache.outputs.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pnpm-store-
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Build package
+        run: pnpm build
+
+      - name: Run ESLint
+        run: pnpm lint
+
+      - name: Run type checking
+        run: pnpm typecheck
+
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v2
+        with:
+          version: ${{ env.PNPM_VERSION }}
+          run_install: false
+
+      - name: Get pnpm store directory
+        id: pnpm-cache
+        shell: bash
+        run: |
+          echo "STORE_PATH=$(pnpm store path)" >> $GITHUB_OUTPUT
+
+      - name: Setup pnpm cache
+        uses: actions/cache@v3
+        with:
+          path: ${{ steps.pnpm-cache.outputs.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pnpm-store-
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Run tests with coverage
+        run: pnpm test:coverage
+
+      - name: Upload coverage to Coveralls
+        uses: coverallsapp/github-action@v2
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          path-to-lcov: ${{ env.COVERAGE_REPORT_PATH }}