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>

extension/widgets-builtin/clock/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "@dashward/widget-clock",
+  "version": "0.0.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "build": "esbuild src/index.ts --bundle --format=esm --outfile=dist/index.js --external:@dashward/widget-sdk",
+    "dev": "esbuild src/index.ts --bundle --format=esm --outfile=dist/index.js --external:@dashward/widget-sdk --watch"
+  },
+  "dependencies": {
+    "@dashward/widget-sdk": "workspace:*"
+  }
+}