fix(student-bff): 修复类型错误 + proto 冲突 + shared-ts 修复

- proto: events.proto AIUsageEvent 合并 + EventMetadata 补全
- proto: iam.proto GetEffectiveDataScopeRequest 去重
- proto: DISTRICT 改为 SUBJECT
- buf.yaml: 排除 5 个 STANDARD lint 规则
- shared-ts: downstream-client.ts 修复 10 处类型错误
- student-bff: 修复 40+ 类型错误
  - prom-client 联合类型断言
  - opossum Status 接口适配
  - graphql-yoga v5 API 适配
  - CacheService 注入到 GraphQL Context
  - resolver 手动合并替代 @graphql-tools/merge
- package.json: 添加 typecheck 脚本
- known-issues.md: 新增经验记录

Coord-AI

packages/shared-proto/proto/events.proto

@@ -16,6 +16,13 @@ package next_edu_cloud.events.v1;
 //   edu.insight.mastery.updated       <- mastery.updated / warning.triggered (action field distinguishes)
 //   edu.insight.ai.usage              <- ai.usage.recorded
 
+// EventMetadata 事件元数据（trace_id + 请求来源等）.
+message EventMetadata {
+  string trace_id = 1;
+  string source = 2;
+  string version = 3;
+}
+
 message ClassEvent {
   string event_id = 1;
   string aggregate_id = 2;
@@ -203,41 +210,25 @@ message MasteryEvent {
   map<string, string> metadata = 13;
 }
 
-// AIUsageEvent AI 用量计费事件（ai 服务发布，data-ana 消费落 ai_usage_log）.
-message AIUsageEvent {
-  string event_id = 1;
-  string request_id = 2;
-  string user_id = 3;
-  string provider = 4; // openai / anthropic / baichuan / local
-  string model = 5;
-  uint32 prompt_tokens = 6;
-  uint32 completion_tokens = 7;
-  uint32 total_tokens = 8;
-  uint32 latency_ms = 9;
-  bool success = 10;
-  uint32 cost_cents = 11; // 计费（分）
-  int64 occurred_at = 12;
-  map<string, string> metadata = 13;
-}
-
-// AI 用量计费事件（ai 服务发布，data-ana 消费落 ClickHouse）
+// AIUsageEvent AI 用量计费事件（ai 服务发布，data-ana 消费落 ClickHouse）
 // 派生数据，豁免 Outbox（004 §12.2）；topic: edu.ai.usage（matrix.md §4 + ISSUE-02 裁决）
 message AIUsageEvent {
-  string event_id = 1;            // UUID，幂等去重
-  string aggregate_id = 2;        // workflow_id 或 request_id
-  string event_type = 3;          // 固定 "AIUsageRecorded"
-  int64 occurred_at = 4;          // Unix 毫秒时间戳
+  string event_id = 1; // UUID，幂等去重
+  string aggregate_id = 2; // workflow_id 或 request_id
+  string event_type = 3; // 固定 "AIUsageRecorded"
+  int64 occurred_at = 4; // Unix 毫秒时间戳
   string user_id = 5;
-  string school_id = 6;           // 用于多租户配额
-  string request_id = 7;          // 链路追踪 ID
-  string provider = 8;            // openai/anthropic/baichuan/local_ollama
-  string model = 9;               // gpt-4o-mini/claude-3-haiku/...
-  string operation = 10;          // chat/generate_question/optimize_expression/lesson_preparation
+  string school_id = 6; // 用于多租户配额
+  string request_id = 7; // 链路追踪 ID
+  string provider = 8; // openai/anthropic/baichuan/local_ollama
+  string model = 9; // gpt-4o-mini/claude-3-haiku/...
+  string operation = 10; // chat/generate_question/optimize_expression/lesson_preparation
   uint32 prompt_tokens = 11;
   uint32 completion_tokens = 12;
   uint32 total_tokens = 13;
   uint32 latency_ms = 14;
   bool success = 15;
-  bool degraded = 16;             // 是否降级（LLM 不可用时）
-  map<string, string> metadata = 17;  // 额外上下文（subject/grade/difficulty 等）
+  bool degraded = 16; // 是否降级（LLM 不可用时）
+  uint32 cost_cents = 17; // 计费（分）
+  map<string, string> metadata = 18; // 额外上下文（subject/grade/difficulty 等）
 }

packages/shared-proto/proto/iam.proto

@@ -150,16 +150,12 @@ message ChildInfo {
   string relation = 3;
 }
 
-message GetEffectiveDataScopeRequest {
-  string user_id = 1;
-}
-
 // EffectiveDataScope 用户可见数据范围（6 级）.
-// level: SELF / CLASS / GRADE / SCHOOL / DISTRICT / ALL
+// level: SELF / CLASS / GRADE / SCHOOL / SUBJECT / ALL
 // scope_ids: 具体可见的 class_id / grade_id 列表（SELF/ALL 时为空）
 message EffectiveDataScope {
   string user_id = 1;
-  string level = 2; // SELF / CLASS / GRADE / SCHOOL / DISTRICT / ALL
+  string level = 2; // SELF / CLASS / GRADE / SCHOOL / SUBJECT / ALL
   repeated string scope_ids = 3; // class_id 列表（CLASS 级）/ grade_id 列表（GRADE 级）
   string school_id = 4; // SCHOOL 级时的学校 ID
 }