feat: streamline arbitrary audio sources

apps/dataset-builder/styles.css

@@ -179,6 +179,14 @@
   margin-top: 32px;
 }
 
+.source-actions {
+  display: flex;
+  flex: 0 0 auto;
+  flex-wrap: wrap;
+  justify-content: flex-end;
+  gap: 10px;
+}
+
 .source-strip-heading h2,
 .asset-shelf h2 {
   margin-bottom: 5px;
@@ -524,10 +532,16 @@
   }
 
   .header-actions,
-  .workspace-tools {
+  .workspace-tools,
+  .source-actions {
     width: 100%;
   }
 
+  .source-actions .button {
+    min-width: 0;
+    flex: 1 1 calc(50% - 5px);
+  }
+
   .scene-workspace {
     padding: 18px;
   }