Extract independent MIT Mortar kit and contribution workflow

playground/index.html

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+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width,initial-scale=1" />
+    <title>Mortar component playground</title>
+  </head>
+  <body>
+    <div id="root"></div>
+    <script type="module" src="/main.tsx"></script>
+  </body>
+</html>

playground/main.tsx

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+import { Suspense, lazy, type ComponentType } from "react";
+import { createRoot } from "react-dom/client";
+import {
+  ThemeProvider,
+  Select,
+  AppearanceControl,
+  PageHeading,
+  Notice,
+} from "../src/index.js";
+import catalog from "../catalog.json";
+import "./styles.css";
+const fixtures = import.meta.glob("../previews/*Preview.tsx");
+const params = new URLSearchParams(location.search);
+const component = params.get("component") || "Button";
+const loader = fixtures[`../previews/${component}Preview.tsx`];
+const Preview = loader
+  ? lazy(loader as () => Promise<{ default: ComponentType }>)
+  : null;
+createRoot(document.getElementById("root")!).render(
+  <ThemeProvider
+    brand={params.get("brand") === "green" ? "green" : "neutral"}
+    initialAppearance={params.get("theme") === "dark" ? "dark" : "light"}
+  >
+    <main className="m-stack p-6 mx-auto max-w-6xl">
+      <PageHeading
+        title="Mortar playground"
+        description="Shared components and shells. No service account required."
+      />
+      <div className="flex flex-wrap gap-4 items-end">
+        <Select
+          label="Component"
+          value={component}
+          options={catalog.components.map((c) => ({
+            value: c.export,
+            label: c.name,
+          }))}
+          onChange={(e) => {
+            params.set("component", e.target.value);
+            location.search = params.toString();
+          }}
+        />
+        <AppearanceControl />
+      </div>
+      <Suspense fallback={<p role="status">Loading preview…</p>}>
+        {Preview ? (
+          <Preview />
+        ) : (
+          <Notice title="Unknown component" tone="danger">
+            Choose a component from the catalogue.
+          </Notice>
+        )}
+      </Suspense>
+    </main>
+  </ThemeProvider>,
+);

playground/styles.css

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+@import "tailwindcss";
+@import "../styles.css";
+@source '../src';
+@source '../previews';