Fixing Angular 21 by migrating all values by signals. (#11)

frontend/src/app/pages/search-publications/search-publications.component.html

@@ -1,13 +1,13 @@
 <h1 i18n>Search results</h1>
-@if((isLoading$ | async) === true) {
-    <h2 i18n>Search in progress...</h2>
-    <mat-spinner></mat-spinner>
-} @else if((isLoaded$ | async) === true) {
-    @if((publications$ | async)?.length) {
-        <app-publication-list [publications$]="publications$"></app-publication-list>
-    } @else {
-        <span i18n>No any result.</span>
-    }
-} @else {
+@if (isLoading()) {
+  <h2 i18n>Search in progress...</h2>
+  <mat-spinner/>
+} @else if (isLoaded()) {
+  @if (publications().length) {
+    <app-publication-list [publications]="publications()"/>
+  } @else {
     <span i18n>No any result.</span>
+  }
+} @else {
+  <span i18n>No any result.</span>
 }