feat(characters): support character-scoped conversations

src/lib/chat/chat_media_cache_client.ts

@@ -7,6 +7,7 @@ import { Result, type Result as ResultT } from "@/utils/result";
 import { localChatMediaRowToBlob } from "./chat_media_blob";
 
 export interface ResolveCachedChatMediaBlobInput {
+  characterId: string;
   messageId: string;
   kind: ChatMediaKind;
 }