feat(openwiki v0.3.1): add YAML frontmatter + install-id markers from initial init run (2026-08-07)

themes.md

@@ -1,3 +1,9 @@
+---
+type: "Reference"
+title: "Themes"
+openwiki_generated: true
+---
+
 # Themes
 
 Recurring topics, signals, and trends observed across Robin's sources. Detailed evidence and item lists live on the relevant `/sources/<connector>.md` or topic page; this file is the index.