chore: initial scaffold of KDC Design System

Initial repository scaffold:
- design.md (google-labs-code/design.md format) as canonical token + guidelines source
- brand assets, foundations, tokens (W3C-style JSON)
- 12 component primitives, each with labeled anatomy.svg and spec README
- light / dark / high-contrast themes, web/mobile/email/print/presentation templates
- docs (getting started, principles, a11y, voice & tone, contributing)
- runnable web example, token build script stub, CI placeholder

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -0,0 +1,10 @@
+# Changelog
+
+All notable changes to the KDC Design System will be documented in this file.
+The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/) and
+this project adheres to [Semantic Versioning](https://semver.org/).
+
+## [Unreleased]
+
+### Added
+- Initial repository scaffold: `design.md`, brand, foundations, components, themes, templates, docs.