Add complete Calendar Elements Demo application

Built comprehensive demo app showcasing 24 calendar components:
- 4 Calendar Views (Month, Week, Day, Agenda)
- 4 Date/Time Pickers (Date, Time, Range, Duration)
- 8 Components (Event Card, Mini Calendar, Headers, Forms, etc.)
- 8 Widgets (Heatmap, Today, Badges, Indicators, etc.)

Features:
- Mist theme with animated gradient background and glassmorphism
- Apple theme with clean solid design
- Dark/light mode support
- Responsive design for all screen sizes
- Signal-based reactive state management
- Comprehensive mock data (13+ events, recurrence rules, time slots)
- Interactive navigation and event handling

Tech stack: Angular 19, TypeScript, SCSS, Luxon, RRule

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

package.json

@@ -0,0 +1,37 @@
+{
+  "name": "calendar-elements-demo",
+  "version": "0.0.1",
+  "description": "Demo application for calendar-elements-ui library",
+  "scripts": {
+    "ng": "ng",
+    "start": "ng serve",
+    "build": "ng build",
+    "watch": "ng build --watch --configuration development",
+    "serve": "ng serve --open"
+  },
+  "private": true,
+  "dependencies": {
+    "@angular/animations": "^19.2.0",
+    "@angular/common": "^19.2.0",
+    "@angular/compiler": "^19.2.0",
+    "@angular/core": "^19.2.0",
+    "@angular/forms": "^19.2.0",
+    "@angular/platform-browser": "^19.2.0",
+    "@angular/platform-browser-dynamic": "^19.2.0",
+    "@angular/router": "^19.2.0",
+    "calendar-elements-ui": "file:../calendar-elements-ui/dist",
+    "base-ui": "file:../sda-frontend/libs/base-ui/dist",
+    "luxon": "^3.5.0",
+    "rrule": "^2.8.1",
+    "rxjs": "~7.8.0",
+    "tslib": "^2.3.0",
+    "zone.js": "~0.15.0"
+  },
+  "devDependencies": {
+    "@angular-devkit/build-angular": "^19.2.0",
+    "@angular/cli": "^19.2.0",
+    "@angular/compiler-cli": "^19.2.0",
+    "@types/luxon": "^3.4.2",
+    "typescript": "~5.7.2"
+  }
+}