fix: use [[:space:]] instead of \s for macOS bash 3.2 compatibility

macOS ships bash 3.2 which does not support \s in =~ regex patterns.
Replace with POSIX [[:space:]] which works on all platforms.

https://claude.ai/code/session_01Y8NseCm28GqE8nQ1Yvg5aa

Author: claude

.github/workflows/setup-stackql-test.yml

@@ -42,14 +42,15 @@ jobs:
         echo "${{ env.registry_list_output }}"
 
         # Validate header row: expect | provider | and | version | columns
-        HEADER_REGEX='\|\s*provider\s*\|\s*version\s*\|'
+        # Use [[:space:]] instead of \s for macOS bash 3.2 compatibility
+        HEADER_REGEX='\|[[:space:]]*provider[[:space:]]*\|[[:space:]]*version[[:space:]]*\|'
         if ! [[ "${{ env.registry_list_output }}" =~ $HEADER_REGEX ]]; then
           echo "Registry list header does not match expected format"
           exit 1
         fi
 
         # Validate at least one data row: | <name> | v<major>.<minor>.<patch> |
-        DATA_ROW_REGEX='\|\s*[a-z][a-z0-9_]*\s*\|\s*v[0-9]+\.[0-9]+\.[0-9]+\s*\|'
+        DATA_ROW_REGEX='\|[[:space:]]*[a-z][a-z0-9_]*[[:space:]]*\|[[:space:]]*v[0-9]+\.[0-9]+\.[0-9]+[[:space:]]*\|'
         if ! [[ "${{ env.registry_list_output }}" =~ $DATA_ROW_REGEX ]]; then
           echo "Registry list does not contain a valid data row"
           exit 1