ci: add codecov coverage reporting

Author: kenryu42

.github/workflows/ci.yml

@@ -1,15 +1,18 @@
 name: CI
 
 on:
+  workflow_dispatch:
   push:
     branches: [main]
     paths:
       - "src/**"
+      - "scripts/**"
       - "tests/**"
   pull_request:
     branches: [main]
     paths:
       - "src/**"
+      - "scripts/**"
       - "tests/**"
 
 concurrency:
@@ -59,8 +62,13 @@ jobs:
         env:
           BUN_INSTALL_ALLOW_SCRIPTS: "@ast-grep/cli"
 
-      - name: Run tests
-        run: AGENT=1 bun test
+      - name: Run tests with coverage
+        run: AGENT=1 bun test --coverage --coverage-reporter=lcov
+
+      - name: Upload coverage reports to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
 
   build:
     runs-on: ubuntu-latest