chore: P0 skeleton

Bootstrap the Dashward repo per arch/UBUNTU-DASHBOARD-SPACE.md:

- pnpm-workspaces monorepo (sdk, extension, container, widgets-builtin/*)
- GNOME extension stub (metadata.json, src/*.ts placeholders for warden,
  guard, supervisor, entry UX, DBus service)
- WebKit container stub (GJS main + page-side runtime + dashboard.html)
- TypeScript widget SDK (defineWidget + types)
- Builtin clock widget as the first SDK consumer example
- DBus interface XML (proto/shell.iface.xml) and shared types
- esbuild configs for extension and container; tsc for SDK
- Design doc copied in at repo root for discoverability

No functional logic yet -- all components are placeholders that compose
in extension.ts so the build chain can be exercised. P1 (workspace
warden) starts next.

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

container/esbuild.config.js

@@ -0,0 +1,34 @@
+import esbuild from 'esbuild';
+
+const watch = process.argv.includes('--watch');
+
+const gjsOpts = {
+  entryPoints: ['src/main.ts'],
+  bundle: true,
+  outfile: 'dist/main.js',
+  format: 'esm',
+  target: 'firefox128',
+  platform: 'neutral',
+  external: ['gi://*', 'system', 'cairo', 'gettext'],
+  sourcemap: 'inline',
+  logLevel: 'info',
+};
+
+const runtimeOpts = {
+  entryPoints: ['runtime/runtime.ts'],
+  bundle: true,
+  outfile: 'dist/runtime.js',
+  format: 'esm',
+  target: 'es2022',
+  platform: 'browser',
+  sourcemap: 'inline',
+  logLevel: 'info',
+};
+
+if (watch) {
+  const c1 = await esbuild.context(gjsOpts);
+  const c2 = await esbuild.context(runtimeOpts);
+  await Promise.all([c1.watch(), c2.watch()]);
+} else {
+  await Promise.all([esbuild.build(gjsOpts), esbuild.build(runtimeOpts)]);
+}