fix: validation (better #8456) (#8461)

* Revert "revert 484e023c0"

This reverts commit c03b70c949.

* also allow pure renote

* fix checks for pure renote

packages/backend/src/server/api/endpoints/notes/search.ts

@@ -35,7 +35,11 @@ export const paramDef = {
 		untilId: { type: 'string', format: 'misskey:id' },
 		limit: { type: 'integer', minimum: 1, maximum: 100, default: 10 },
 		offset: { type: 'integer', default: 0 },
-		host: { type: 'string', nullable: true },
+		host: {
+			type: 'string',
+			nullable: true,
+			description: 'The local host is represented with `null`.',
+		},
 		userId: { type: 'string', format: 'misskey:id', nullable: true, default: null },
 		channelId: { type: 'string', format: 'misskey:id', nullable: true, default: null },
 	},