Add FlagType and updateFlag API method to frontend

Add FlagType to type definitions and flag field to SubmissionOut/SubmissionAll
interfaces. Add updateFlag method to Submission API client.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/api.ts

@@ -1,6 +1,6 @@
 import axios from "axios"
 import { router } from "./router"
-import type { TutorialIn, ChallengeIn } from "./utils/type"
+import type { TutorialIn, ChallengeIn, FlagType } from "./utils/type"
 import { BASE_URL, STORAGE_KEY } from "./utils/const"
 
 const http = axios.create({
@@ -167,6 +167,11 @@ export const Submission = {
     const res = await http.put(`/submission/${id}/score`, { score })
     return res.data
   },
+
+  async updateFlag(id: string, flag: FlagType) {
+    const res = await http.put(`/submission/${id}/flag`, { flag })
+    return res.data
+  },
 }
 
 export const Prompt = {