feat(ai): AiState + AiModule (ErpModule impl + 权限 + 路由骨架)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/erp-ai/src/lib.rs

@@ -1,9 +1,14 @@
 pub mod dto;
 pub mod entity;
 pub mod error;
+pub mod handler;
+pub mod module;
 pub mod prompt;
 pub mod provider;
 pub mod sanitization;
 pub mod service;
+pub mod state;
 
 pub use error::{AiError, AiResult};
+pub use module::AiModule;
+pub use state::AiState;