Initial commit: kanban-elements-demo app

Interactive Angular 19 demo for @sda/kanban-elements-ui with board
view, pipeline view, swimlanes, drag-and-drop, WIP limits, custom
card templates, and dark mode toggle.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tsconfig.app.json

@@ -0,0 +1,13 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "./out-tsc/app",
+    "types": []
+  },
+  "files": [
+    "src/main.ts"
+  ],
+  "include": [
+    "src/**/*.d.ts"
+  ]
+}