ci: integrate codecov coverage reporting

.github/workflows/ci.yml

@@ -63,7 +63,7 @@ jobs:
         run: npm run format:check
 
   test:
-    name: Test
+    name: Test and Coverage
     runs-on: ubuntu-latest
     timeout-minutes: 15
     steps:
@@ -84,6 +84,23 @@ jobs:
         env:
           CI: true
 
+      - name: Generate coverage report
+        run: npm run test:coverage
+        env:
+          CI: true
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          files: ./coverage/lcov.info
+          flags: unit
+          name: unit-coverage
+          disable_search: true
+          fail_ci_if_error: true
+          verbose: true
+        env:
+          CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
+
   typecheck:
     name: Type Check
     runs-on: ubuntu-latest