chore: add codecov github action

.github/workflows/codecov.yml

@@ -0,0 +1,72 @@
+# Run cargo-llvm-cov and upload to codecov.io
+
+name: Code Coverage
+
+on:
+  workflow_dispatch:
+  push:
+    # branches:
+    #   - main
+    paths:
+      - '**.rs'
+      - '.github/workflows/codecov.yml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.ref_name != 'main' }}
+
+jobs:
+  coverage:
+    name: Code Coverage
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: moonrepo/setup-rust@v1
+        with:
+          bins: just, taplo-cli
+          cache-base: main
+          components: clippy,rustfmt,llvm-tools-preview
+
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@v2
+        with:
+          tool: cargo-llvm-cov
+
+      - name: Run
+        run: cargo llvm-cov --lcov --output-path lcov.info
+
+      - name: Upload Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: codecov
+          path: lcov.info
+
+  # codecov often fails, use another workflow for retry
+  upload-codecov:
+    name: Upload coverage file
+    runs-on: ubuntu-latest
+    needs: coverage
+    # Check if the event is not triggered by a fork by checking whether CODECOV_TOKEN is set
+    env:
+      CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
+    steps:
+      - name: Checkout
+        if: env.CODECOV_TOKEN
+        uses: actions/checkout@v4
+
+      - name: Download coverage file
+        if: env.CODECOV_TOKEN
+        uses: actions/download-artifact@v4
+        with:
+          name: codecov
+
+      - name: Upload to codecov.io
+        if: env.CODECOV_TOKEN
+        uses: codecov/codecov-action@v4
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          fail_ci_if_error: true
+          files: lcov.info