chore: add link checker to CI workflow

.github/workflows/ci.yaml

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index accfcc7..667f3dc 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -23,6 +23,7 @@
         runs-on: ubuntu-latest
         steps:
             - uses: actions/checkout@v6
+            - uses: lycheeverse/lychee-action@v2
             - id: bazel-version
               name: Prepare 'bazel-version' matrix axis
               run: |