refactor(chat): tighten media cache boundaries

src/data/storage/chat/local_chat_db.ts

@@ -12,6 +12,7 @@
  */
 
 import Dexie, { type Table } from "dexie";
+import type { ChatMediaKind } from "@/data/dto/chat";
 import type {
   ChatImageData,
   ChatLockDetailData,
@@ -32,13 +33,11 @@ export interface LocalMessageRow {
   sessionId: string;
 }
 
-export type LocalChatMediaKind = "image" | "audio";
-
 export interface LocalChatMediaRow {
   cacheKey: string;
   ownerKey: string;
   messageId: string;
-  kind: LocalChatMediaKind;
+  kind: ChatMediaKind;
   remoteUrl: string;
   blob: Blob;
   mimeType: string;