fix(ui): normalize infill alpha to 0-255 when building infill nodes

The browser/UI uses float 0-1 for alpha, while backend uses 0-255. We need to normalize the value when building the infill nodes for outpaint.

Author: psychedelicious

invokeai/frontend/web/src/features/nodes/util/graph/graphBuilderUtils.ts

@@ -106,10 +106,12 @@ export const getInfill = (
   }
 
   if (infillMethod === 'color') {
+    const { a, ...rgb } = infillColorValue;
+    const color = { ...rgb, a: Math.round(a * 255) };
     return g.addNode({
       id: 'infill_rgba',
       type: 'infill_rgba',
-      color: infillColorValue,
+      color,
     });
   }