feat: nwaifu-ui lib with btn

src/app/app.component.html

@@ -1,6 +1,11 @@
 <div class="btns">
-  <app-upload-btn (fileLoaded)="onFileLoaded($event)"></app-upload-btn>
-  <app-clear-btn (clear)="onClearClicked()"></app-clear-btn>
+  <nwui-button (click)="fileInput.click()">
+    <span><i class="lni lni-upload"></i> Upload</span>
+    <input type="file" (change)="submitFile($event)" #fileInput style="display: none" />
+  </nwui-button>
+  <nwui-button (click)="onClearClicked()">
+    <span><i class="lni lni-trash-can"></i> Clear</span>
+  </nwui-button>
 </div>
 <app-text-list [elements]="elements"></app-text-list>
 <router-outlet></router-outlet>