fix: use case-insensitive grep and GH Actions notice for lastupdated skip

Author: Copilot

.github/workflows/sphinxbuild.yml

@@ -574,14 +574,14 @@ jobs:
           # Check for meaningful changes, ignoring:
           # - lastupdated date lines in HTML (Sphinx build-time timestamps)
           # - epub/pdf binaries (they regenerate automatically alongside HTML)
-          meaningful_html=$(git diff HEAD -- '*.html' | grep -E '^[+-]' | grep -v '^[+-]{3}' | grep -v 'lastupdated\|Last updated on' | wc -l)
+          meaningful_html=$(git diff HEAD -- '*.html' | grep -E '^[+-]' | grep -v '^[+-]{3}' | grep -ivE 'lastupdated|Last updated on' | wc -l)
           other_changes=$(git diff --name-only HEAD | grep -cvE '\.(html|epub|pdf)$' || true)
 
           if [ "$meaningful_html" -gt 0 ] || [ "$other_changes" -gt 0 ]; then
             echo "has_changes=true" >> $GITHUB_OUTPUT
           else
             echo "has_changes=false" >> $GITHUB_OUTPUT
-            echo "Skipping PR: only lastupdated timestamps or epub/pdf binaries changed"
+            echo "::notice::Skipping deploy PR: only lastupdated timestamps or epub/pdf binaries changed"
           fi
 
       - name: Strip noindex from stable docs