feat(ui): animated boot splash and loading screen

Show a Lottie-animated splash while the app bundle boots and dismiss it
once WebAppComponent initialises, plus a reusable mifosx-loading-screen
component with loading and error animations. lottie.min.js is served
from the lottie-web package instead of being vendored into src/assets.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/shared/shared.module.ts

@@ -30,6 +30,7 @@ import { SearchToolComponent } from './search-tool/search-tool.component';
 import { KeyboardShortcutsDialogComponent } from './keyboard-shortcuts-dialog/keyboard-shortcuts-dialog.component';
 import { ServerSelectorComponent } from './server-selector/server-selector.component';
 import { TenantSelectorComponent } from './tenant-selector/tenant-selector.component';
+import { LoadingScreenComponent } from './loading-screen/loading-screen.component';
 
 /** Custom Modules */
 import { IconsModule } from './icons.module';
@@ -116,9 +117,11 @@ import { DatetimePickerStubComponent } from './datetime-picker-stub/datetime-pic
     DropdownComponent,
     InputAmountComponent,
     InputPasswordComponent,
+    LoadingScreenComponent,
     DatetimePickerStubComponent // temporarily added stub for datetime picker
   ],
   exports: [
+    LoadingScreenComponent,
     FileUploadComponent,
     FooterComponent,
     LanguageSelectorComponent,