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/CHANGELOG.md

@@ -0,0 +1,39 @@
+# Changelog
+
+All notable changes to the Shibui theme will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+- Reading time estimation feature with `showreadingtime` parameter
+- Last modified date display option with `showlastmod` parameter
+- Theme configuration parameters documentation
+- ARIA labels to navigation elements for improved accessibility
+- Preconnect/DNS prefetch for external resources (mermaid CDN)
+- Enhanced 404 page with additional navigation options
+- CSS styling for reading time and lastmod indicators
+
+### Changed
+- Reorganized CSS loading to remove redundant custom.css import from main.css
+- Improved semantic HTML structure with landmark roles
+
+### Fixed
+- None yet
+
+## [0.1.0] - 2025-11-20
+
+### Added
+- Initial release of Shibui theme
+- Minimalist design following Shibui (渋い) aesthetics
+- Terminal-inspired navigation
+- Clean typography with monospace font
+- Automatic dark/light theme support via CSS variables
+- Nested heading counters
+- Zero JavaScript (pure CSS solutions)
+- Table of contents support
+- Tags and taxonomy support
+- Responsive layout
+- Print styles