feat(voyage): scaffold playground/ with DS vendor sync — v4.2 Step 5

- playground/voyage-playground.html: minimal skeleton (DOCTYPE, app-header, guide-panel, aria-live region, skip-to-main link). Steps 8-11 will extend with render-pipeline + creation gestures + sidebar + export.
- playground/vendor/playground-design-system/: synced via 'node scripts/sync-design-system.mjs voyage' (27 files + MANIFEST.json with source_commit + sync_date + SHA-256 per file).
- tests/playground/voyage-playground.test.mjs: 8 tests pinning HTML existence, DOCTYPE, no-external-URLs, no-marked, A11Y skip-to-main + aria-live, MANIFEST.json structure, vendored DS files present.
- shared/PLAYGROUND-MAINTENANCE.md: consumer list updated 5 -> 6 (added voyage).

playground/vendor/playground-design-system/fonts/LICENSES.md

@@ -0,0 +1,42 @@
+# Font Licenses
+
+All three font families bundled with Playground Design System are licensed
+under the SIL Open Font License, Version 1.1 (OFL-1.1). They are free to
+use, modify, embed, and redistribute under the terms of OFL-1.1.
+
+Full license text per family:
+
+- **Inter** (Regular, Medium, SemiBold, Bold) — `LICENSE-Inter.txt`
+  Copyright (c) 2016 The Inter Project Authors
+  Source: https://github.com/rsms/inter
+  Version bundled: 4.0
+
+- **JetBrains Mono** (Regular, Medium, SemiBold) — `LICENSE-JetBrainsMono.txt`
+  Copyright 2020 The JetBrains Mono Project Authors
+  Source: https://github.com/JetBrains/JetBrainsMono
+  Version bundled: 2.304
+
+- **Source Serif 4** (Regular, Semibold) — `LICENSE-SourceSerif4.md`
+  Copyright 2014–2023 Adobe (Reserved Font Name "Source")
+  Source: https://github.com/adobe-fonts/source-serif
+  Version bundled: 4.005
+
+## Provenance
+
+Files in this directory were obtained from the upstream release artifacts
+linked above on 2026-05-03. Source Serif 4 woff2 files were generated locally
+from the desktop OTF release using `fonttools ttLib.woff2 compress`; all
+others are unmodified from upstream webfont releases.
+
+## Why bundled
+
+These fonts ship with the design system to eliminate runtime requests to
+external CDNs (e.g., fonts.googleapis.com). This guarantees:
+
+- No data leakage about end-user IPs / User-Agents to third parties.
+- GDPR compliance for Norwegian public-sector deployments.
+- Functioning Playgrounds in offline / air-gapped environments.
+
+Each Playground HTML loads `../shared/playground-design-system/fonts.css`,
+which declares all `@font-face` rules pointing at the .woff2 files in this
+directory.