fix: apply default page layout so subpages render with CSS

Add layout: page to the defaults block so all vault pages without
an explicit layout (e.g. /now/, /kaaro/) get the full site chrome.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: karx

_config.yml

@@ -12,6 +12,7 @@ defaults:
   - scope:
       path: ""
     values:
+      layout: "page"
       render_with_liquid: false
 
 # Don't crash on files with missing frontmatter