feat(ai): 知识库 V2 Handler + 路由注册 + State 初始化

5 个端点：GET/POST /ai/knowledge-bases, GET/PUT/DELETE /ai/knowledge-bases/{id}
AiState 新增 knowledge_v2 字段，main.rs 初始化。

crates/erp-ai/src/state.rs

@@ -12,6 +12,7 @@ use crate::service::chat_session::ChatSessionService;
 use crate::service::feature_flag_service::FeatureFlagService;
 use crate::service::insight_service::InsightService;
 use crate::service::knowledge::KnowledgeService;
+use crate::service::knowledge_v2::KnowledgeV2Service;
 use crate::service::prompt::PromptService;
 use crate::service::quota::QuotaService;
 use crate::service::risk_service::RiskService;
@@ -34,6 +35,7 @@ pub struct AiState {
     pub insight_service: Arc<InsightService>,
     pub feature_flags: Arc<FeatureFlagService>,
     pub knowledge: Arc<KnowledgeService>,
+    pub knowledge_v2: Arc<KnowledgeV2Service>,
     pub chat_session: Arc<ChatSessionService>,
     pub chat_message: Arc<ChatMessageService>,
 }