Add retry loop to CI tool install steps

Wraps TinyTeX and Chrome Headless Shell install steps in a 3-attempt
retry loop with 15s delay. Uses GitHub Actions annotations (::warning::
and ::error::) for visibility. Defense-in-depth alongside the internal
download retry added to downloadWithProgress.

Author: cderv

.github/workflows/test-install.yml

@@ -40,11 +40,27 @@ jobs:
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
-          quarto install tinytex
+          for attempt in 1 2 3; do
+            if quarto install tinytex; then
+              exit 0
+            fi
+            echo "::warning::Attempt $attempt failed, retrying in 15s..."
+            sleep 15
+          done
+          echo "::error::TinyTeX install failed after 3 attempts"
+          exit 1
 
       - name: Install Chrome Headless Shell
         run: |
-          quarto install chrome-headless-shell --no-prompt
+          for attempt in 1 2 3; do
+            if quarto install chrome-headless-shell --no-prompt; then
+              exit 0
+            fi
+            echo "::warning::Attempt $attempt failed, retrying in 15s..."
+            sleep 15
+          done
+          echo "::error::Chrome Headless Shell install failed after 3 attempts"
+          exit 1
 
       - name: Verify tools with quarto check
         run: |