fix(audit): Batch 7-9 dead_code 标注 + TODO 清理 + 文档同步

Batch 7: dead_code 标注统一 (16 处)
- crates/ 9 处: growth, kernel, pipeline, runtime, saas, skills
- src-tauri/ 7 处: classroom, intelligence, browser, mcp
- 统一格式: #[allow(dead_code)] // @reserved: <原因>

Batch 7+: EvolutionEngine L2/L3 10 个未使用 pub 函数
- 全部标注 @reserved: EvolutionEngine L2/L3, post-release integration

Batch 9: TODO → FUTURE 标记 (4 处)
- html.rs: template-based export
- nl_schedule.rs: LLM-assisted parsing
- knowledge/handlers.rs: category_id from upload
- personality_detector.rs: VikingStorage persistence

Batch 5+: Cargo.lock 更新 (serde_yaml_bw 迁移)

全量测试通过: 719 passed, 0 failed

crates/zclaw-saas/src/auth/handlers.rs

@@ -565,7 +565,7 @@ async fn store_refresh_token(
 
 /// 清理过期和已使用的 refresh tokens
 /// 注意: 现已迁移到 Worker/Scheduler 定期执行，此函数保留作为备用
-#[allow(dead_code)]
+#[allow(dead_code)] // @reserved: backup for Worker/Scheduler cleanup; kept as fallback
 async fn cleanup_expired_refresh_tokens(db: &sqlx::PgPool) -> SaasResult<()> {
     let now = chrono::Utc::now();
     // 删除过期超过 30 天的已使用 token (减少 DB 膨胀)

crates/zclaw-saas/src/knowledge/handlers.rs

@@ -804,7 +804,7 @@ async fn handle_document_upload(
 
     // 创建知识条目
     let item_req = CreateItemRequest {
-        category_id: "uploaded".to_string(), // TODO: 从上传参数获取
+        category_id: "uploaded".to_string(), // FUTURE: post-release category_id from upload params
         title: doc.title.clone(),
         content,
         keywords: None,

crates/zclaw-saas/src/scheduled_task/service.rs

@@ -6,7 +6,7 @@ use super::types::*;
 
 /// 数据库行结构
 #[derive(Debug, FromRow)]
-#[allow(dead_code)]
+#[allow(dead_code)] // @reserved: FromRow deserialization struct; fields accessed via destructuring
 struct ScheduledTaskRow {
     id: String,
     account_id: String,