init: scaffold OPENBUREAU site with shibui-derived theme

- Hugo site for openbureau.ch (Deutsch, i18n-ready for EN/IT)
- Theme themes/openbureau/ = local copy of shibui, customized via
  site-level layouts and assets to keep the theme reference clean
- Editorial typography stack: Newsreader serif body, Space Grotesk
  display, Inter for listings, IBM Plex Mono for technical meta
- Content structure: library/ (Theorie, Büroführung, Software) with
  manifest and colophon at root; software is a library category, not
  a separate top-level
- Three views over one source: Journal (chronological home),
  Library (atlas grouped by section + tag cloud), single articles

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

themes/openbureau/hugo.toml

@@ -0,0 +1,25 @@
+baseURL = 'https://example.org/'
+languageCode = 'en-US'
+title = 'My New Hugo Site'
+
+[menus]
+  [[menus.main]]
+    name = 'Home'
+    pageRef = '/'
+    weight = 10
+
+  [[menus.main]]
+    name = 'Posts'
+    pageRef = '/posts'
+    weight = 20
+
+  [[menus.main]]
+    name = 'Tags'
+    pageRef = '/tags'
+    weight = 30
+
+[module]
+  [module.hugoVersion]
+    extended = false
+    min = '0.93.0'
+