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>

docs/voice-and-tone/README.md

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+# Voice & Tone
+
+**Voice (constant):** clear, confident, human.
+**Tone (situational):** warm in onboarding, terse in errors, neutral in data.
+
+## Writing rules
+
+- Sentence case for headings, buttons, and labels.
+- Active voice. "Save changes" not "Changes will be saved".
+- Lead with what the user gets, not what we did.
+- Numbers as digits (`3 items`, not `three items`).
+- One idea per sentence in error messages.