docs: bring repo up to repo-standard (LICENSE, Non-goals, description sync)

The repo-standard gate reported 5 ERROR and 1 WARN for this shared-asset:

- FILE-MISSING / LICENSE-CLAIMED-ABSENT: README cited MIT with no LICENSE
  file backing it. Added the MIT text used by the sibling repos.
- HEADING-MISSING: added `## Non-goals` so a reader can answer "is this for
  me?" without reading the component tables.
- README-DESC + DESC-TOO-LONG: the forge description was 181 codepoints
  (bound 180) and claimed a "generated manifest" that does not exist in this
  repo. Rewrote it to 165 codepoints covering only what is here, and made the
  README opening line identical so description == README holds.
- README-H1 (WARN): title-cased H1 was drift, not branding — CHANGELOG.md
  already uses the repo name. Aligned to `# playground-design-system`.

Also corrected the stale `**Version:** 0.1` line on the first screen; the
CHANGELOG is at 0.6.0. It now points at CHANGELOG.md instead of restating a
number that has to be maintained twice.

Gate re-run: 0 ERROR, 0 WARN, 10 OK, 1 SKIP (VERSION-UNAVAILABLE — this is a
CSS asset with no package manifest, so there is no version to compare).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0143xZ1etAuoHVEngJQmDEqe

README.md

@@ -1,8 +1,18 @@
-# Playground Design System
+# playground-design-system
 
-A shared design system for plugin Playgrounds — visual self-service UIs that complement terminal slash-commands. Built for Norwegian public sector with WCAG 2.1 AA compliance, Aksel/Digdir-aligned aesthetics, and self-contained HTML deployment.
+Vendored, framework-free CSS design system for plugin playgrounds — design tokens, four component tiers, self-hosted fonts, and file:// operation with no build step.
 
-**Version:** 0.1 (Phase 1 — 2026-05-02)
+Playgrounds are the visual self-service UIs that complement a plugin's terminal slash-commands. This system gives them one shared visual language: Aksel/Digdir-aligned aesthetics for Norwegian public-sector users, WCAG 2.1 AA contrast and focus handling, and pages that open straight from disk with no server.
+
+**Version:** 0.6.0 — see [CHANGELOG.md](CHANGELOG.md).
+
+## Non-goals
+
+- **Not a JavaScript component library.** The system is CSS-only. Interactivity (tab state, sidepanel toggling, live-meter updates) is wired by each Playground in vanilla JS.
+- **Not a general-purpose web UI kit.** Scope is the Playgrounds in this marketplace; Aksel/Digdir conventions and domain visuals (NS 5814 matrices, EU AI Act tiers) are baked in rather than configurable.
+- **No build step, bundler or npm package.** Files are vendored and linked with plain `<link>` tags. Nothing is compiled, and nothing is published to a package registry.
+- **No icon set.** Iconography is left to each Playground so the shared system stays small.
+- **Not open to pull requests.** Solo project — see [Contributing](#contributing).
 
 ## Provenance