feat: add Angular workspace with demo app and library build

- Restructure into standard Angular library workspace
- Library source in projects/ngx-pretext-table/
- Demo app in src/ using PretextVirtualScrollDirective
- Switch @chenglou/pretext dependency to npm registry (^0.0.4)
- Fix moduleResolution to "bundler" for Angular 17 compatibility

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

src/main.ts

@@ -0,0 +1,4 @@
+import { bootstrapApplication } from '@angular/platform-browser';
+import { AppComponent } from './app/app.component';
+
+bootstrapApplication(AppComponent).catch(err => console.error(err));