fix: remove repo name from basePath when using custom domain

Custom domain (dev.codebuilder.org) doesn't include the repo name in the
URL path, so basePath should be /preview/<branch> not /codebuilder-frontend/preview/<branch>

Author: actions-user

.github/workflows/nextjs-static-gh-pages.yml

@@ -28,6 +28,9 @@ jobs:
         id: vars
         run: |
           REPO_NAME="${{ github.event.repository.name }}"
+          # Custom domain means no repo name prefix in the URL path.
+          # Set CUSTOM_DOMAIN to your domain, or leave empty to use github.io/<repo> URLs.
+          CUSTOM_DOMAIN="dev.codebuilder.org"
 
           # Get the branch name (works for both push and PR events)
           if [ "${{ github.event_name }}" = "pull_request" ]; then
@@ -39,16 +42,26 @@ jobs:
           # Sanitize branch name for use in URL paths
           SAFE_BRANCH=$(echo "$BRANCH" | sed 's/[^a-zA-Z0-9._-]/-/g')
 
+          if [ -n "$CUSTOM_DOMAIN" ]; then
+            BASE_URL="https://${CUSTOM_DOMAIN}"
+          else
+            BASE_URL="https://${{ github.repository_owner }}.github.io/${REPO_NAME}"
+          fi
+
           if [ "$BRANCH" = "main" ]; then
-            echo "base_path=/${REPO_NAME}" >> $GITHUB_OUTPUT
+            if [ -n "$CUSTOM_DOMAIN" ]; then
+              echo "base_path=" >> $GITHUB_OUTPUT
+            else
+              echo "base_path=/${REPO_NAME}" >> $GITHUB_OUTPUT
+            fi
             echo "dest_dir=" >> $GITHUB_OUTPUT
             echo "keep_files=false" >> $GITHUB_OUTPUT
-            echo "preview_url=https://${{ github.repository_owner }}.github.io/${REPO_NAME}/" >> $GITHUB_OUTPUT
+            echo "preview_url=${BASE_URL}/" >> $GITHUB_OUTPUT
           else
-            echo "base_path=/${REPO_NAME}/preview/${SAFE_BRANCH}" >> $GITHUB_OUTPUT
+            echo "base_path=/preview/${SAFE_BRANCH}" >> $GITHUB_OUTPUT
             echo "dest_dir=preview/${SAFE_BRANCH}" >> $GITHUB_OUTPUT
             echo "keep_files=true" >> $GITHUB_OUTPUT
-            echo "preview_url=https://${{ github.repository_owner }}.github.io/${REPO_NAME}/preview/${SAFE_BRANCH}/" >> $GITHUB_OUTPUT
+            echo "preview_url=${BASE_URL}/preview/${SAFE_BRANCH}/" >> $GITHUB_OUTPUT
           fi
 
           echo "branch=$BRANCH" >> $GITHUB_OUTPUT