fix: use absolute path for lychee --base in CI

Lychee v2 requires --base to be a URL or absolute path. Use
github.workspace to construct the absolute path.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: braboj

.github/workflows/build.yml

@@ -33,5 +33,5 @@ jobs:
       - name: Check links
         uses: lycheeverse/lychee-action@v2
         with:
-          args: --base astro-site/dist astro-site/dist
+          args: --base ${{ github.workspace }}/astro-site/dist astro-site/dist
           fail: true

.github/workflows/deploy.yml

@@ -42,7 +42,7 @@ jobs:
       - name: Check links
         uses: lycheeverse/lychee-action@v2
         with:
-          args: --base astro-site/dist astro-site/dist
+          args: --base ${{ github.workspace }}/astro-site/dist astro-site/dist
           fail: true
 
       - name: Upload artifact