feat: update VmSkuOption and related components to use non-nullable numeric types

app/backend/src/azure-service.ts

@@ -169,13 +169,12 @@ export class AzureImageService {
       .filter((value): value is string => Boolean(value));
   }
 
-  private toNumber(value: string | undefined): number | null {
+  private toNumber(value: string | undefined): number {
     if (!value) {
-      return null;
+      return 0;
     }
 
     const parsed = Number.parseFloat(value);
-    return Number.isFinite(parsed) ? parsed : null;
+    return Number.isFinite(parsed) ? parsed : 0;
   }
-
 }

app/backend/src/types.ts

@@ -22,7 +22,7 @@ export type VmSkuOption = {
   size: string;
   family: string;
   tier: string;
-  vcpus: number | null;
-  memoryGb: number | null;
-  maxDataDiskCount: number | null;
+  vcpus: number;
+  memoryGb: number;
+  maxDataDiskCount: number;
 };