fix: allow visibility-only setup updates without name

updateSetupSchema required name as mandatory, causing ZodError when
ShareModal sent visibility-only updates. Made name optional in update
schema and guarded against setting undefined name in service layer.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/server/services/setup.service.ts

@@ -183,9 +183,11 @@ export async function updateSetup(
 	if (!existing) return null;
 
 	const updateData: Record<string, unknown> = {
-		name: data.name,
 		updatedAt: new Date(),
 	};
+	if (data.name !== undefined) {
+		updateData.name = data.name;
+	}
 	if (data.visibility !== undefined) {
 		updateData.visibility = data.visibility;
 	}

src/shared/schemas.ts

@@ -96,7 +96,7 @@ export const createSetupSchema = z.object({
 });
 
 export const updateSetupSchema = z.object({
-	name: z.string().min(1, "Setup name is required"),
+	name: z.string().min(1, "Setup name is required").optional(),
 	visibility: z.enum(["private", "link", "public"]).optional(),
 });