feat(ai): SuggestionService — 建议记录 CRUD + 状态流转

- create_suggestions: 批量创建建议记录，关联分析 ID 和 baseline 快照
- list_by_analysis: 按 analysis_id 查询建议列表（带 tenant_id 过滤 + 软删除）
- list_pending: 查询待审批建议
- update_status: 更新状态（带乐观锁 + tenant_id 过滤）
- mark_parse_failed: 解析失败时记录日志
- AiState 新增 suggestion 字段

crates/erp-ai/src/state.rs

@@ -6,6 +6,7 @@ use sea_orm::DatabaseConnection;
 
 use crate::service::analysis::AnalysisService;
 use crate::service::prompt::PromptService;
+use crate::service::suggestion::SuggestionService;
 use crate::service::usage::UsageService;
 
 #[derive(Clone)]
@@ -15,5 +16,6 @@ pub struct AiState {
     pub analysis: Arc<AnalysisService>,
     pub prompt: Arc<PromptService>,
     pub usage: Arc<UsageService>,
+    pub suggestion: Arc<SuggestionService>,
     pub health_provider: Arc<dyn HealthDataProvider>,
 }