Add two new blog posts and support preview frontmatter

- Add "I Thought I Had 15 Minutes" post about standup automation (draft)
- Add "Why I Self-Host My Social Media" post about YunoHost setup
- Update list.html to use preview param for homepage listings, falling back to description

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

layouts/_default/list.html

@@ -15,7 +15,9 @@
           {{ end }}
           <span class="posts-list-item-description">
             <div>
-              {{ if .Description }}
+              {{ if .Params.preview }}
+                <br />{{ .Params.preview }}<br />(more inside)<br /><br />
+              {{ else if .Description }}
                 <br />{{ .Description }}<br />(more inside)<br /><br />
               {{ else }}
                 {{ .Content }}