Add grid to particle drawer

frontend/src/app/pages/particles/components/render-container/render-container.component.html

@@ -5,6 +5,10 @@
         <mat-label>Opacity</mat-label>
         <input matInput type="number" [(ngModel)]="opacity" min="0" max="1" step="0.01" placeholder="">
       </mat-form-field>
+      <mat-form-field appearance="outline" style="width: 12ch; margin-left: 8px;">
+        <mat-label>Grid density</mat-label>
+        <input matInput type="number" [(ngModel)]="gridDensity" min="1" max="64" step="1" placeholder="">
+      </mat-form-field>
     </div>
     <div class="button-row">
       <button mat-mini-fab color="primary" (click)="resetCamera()"
@@ -26,6 +30,11 @@
               [matTooltip]="isPlaneLocked ? 'Unlock plane' : 'Lock plane'">
         <mat-icon>{{ isPlaneLocked ? 'lock' : 'lock_open' }}</mat-icon>
       </button>
+
+      <button mat-mini-fab color="primary" (click)="gridVisible = !gridVisible"
+              [matTooltip]="gridVisible ? 'Hide grid' : 'Show grid'">
+        <mat-icon>{{ gridVisible ? 'grid_off' : 'grid_on' }}</mat-icon>
+      </button>
     </div>
 
     @if (isPlaneLocked) {