test(card): SetRedEtherAsync helper for create-path tests

SVSim.UnitTests/Infrastructure/SVSimTestFactory.cs

@@ -315,6 +315,20 @@ internal sealed class SVSimTestFactory : WebApplicationFactory<Program>
         await db.SaveChangesAsync();
     }
 
+    /// <summary>
+    /// Sets the viewer's RedEther balance to <paramref name="amount"/>. Call this AFTER
+    /// <see cref="SeedOwnedCardAsync"/>, which resets RedEther to 0. Create tests use this
+    /// to give the viewer enough vials to craft.
+    /// </summary>
+    public async Task SetRedEtherAsync(long viewerId, ulong amount)
+    {
+        using var scope = Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        var viewer = await db.Viewers.FirstAsync(v => v.Id == viewerId);
+        viewer.Currency.RedEther = amount;
+        await db.SaveChangesAsync();
+    }
+
     /// <summary>
     /// Puts <paramref name="count"/> copies of <paramref name="cardId"/> into the viewer's deck
     /// in the given format + slot. Tests use this to set up deck-strip scenarios for /card/destruct.