feat(首页): 登录后不再弹「登录速报」，上次来做了什么、哪道还没做对放进首页，带「接着做」

- 新接口 /me/last-visit：上次登录到这次登录之间的题库提交，不调 AI（原来要同步等模型最长 60 秒弹框才出来）
- 班里今天在做时让位给班里卡，只在卡底留一句；班里那天就是上次来那天时两张卡合成一张
- 第一次登录说「欢迎来到判题狗」，隔了 30 天以上说「好久不见」
- 删掉弹框、store 和 /ai/login-summary

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/contract/src/ai.ts

@@ -263,20 +263,6 @@ export const aiAnalysisRecordSchema = z.object({
   username: z.string().optional(),
 })
 
-export const loginSummarySchema = z.object({
-  summary: z.object({
-    start: z.string(),
-    end: z.string(),
-    newProblemCount: z.number().int(),
-    submissionCount: z.number().int(),
-    acceptedCount: z.number().int(),
-    solvedCount: z.number().int(),
-    flowchartSubmissionCount: z.number().int(),
-  }),
-  analysis: z.string(),
-  analysisError: z.string().optional(),
-})
-
 export type Grade = z.infer<typeof gradeSchema>
 export type DurationData = z.infer<typeof durationDataSchema>
 export type SolvedProblem = z.infer<typeof solvedProblemSchema>
@@ -286,7 +272,6 @@ export type AiDetail = z.infer<typeof aiDetailSchema>
 export type SolvedList = z.infer<typeof solvedListSchema>
 export type HeatmapItem = z.infer<typeof heatmapItemSchema>
 export type AiAnalysisRecord = z.infer<typeof aiAnalysisRecordSchema>
-export type LoginSummary = z.infer<typeof loginSummarySchema>
 
 export type AiAnalysisRequest = z.infer<typeof aiAnalysisRequestSchema>
 export type AiHintRequest = z.infer<typeof aiHintRequestSchema>