feat: create ai-elements-ui demo application

Demo app showcasing ai-elements-ui components:
- AI Canvas with resizable split-panel layout
- Conversation history sidebar
- Avatar with animated states (idle, thinking, speaking)
- Typing indicators (dots, pulse, wave variants)
- Confidence meters (bar, gauge, dots, ring variants)
- Code blocks with syntax highlighting
- Skeleton loaders for various content types

Uses base-ui design tokens and Apple theme for styling.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tsconfig.json

@@ -16,7 +16,14 @@
     "moduleResolution": "bundler",
     "importHelpers": true,
     "target": "ES2022",
-    "module": "ES2022"
+    "module": "ES2022",
+    "baseUrl": ".",
+    "paths": {
+      "base-ui": ["../sda-frontend/libs/base-ui/dist"],
+      "base-ui/*": ["../sda-frontend/libs/base-ui/dist/*"],
+      "ai-elements-ui": ["../ai-elements-ui/dist"],
+      "ai-elements-ui/*": ["../ai-elements-ui/dist/*"]
+    }
   },
   "angularCompilerOptions": {
     "enableI18nLegacyMessageIdFormat": false,