refactor: 重构 core 包目录结构并消除旧版 mod.rs

- 优化 剥离 models,algo 层并平铺业务模块
- 重构 统一使用现代 filename.rs + 文件夹结构替代旧版 mod.rs

ddddocr-tract/src/det/session.rs

@@ -1,4 +1,4 @@
-use crate::loader::{ModelLoader, ModelSession, ModelType};
+use crate::loader::ModelLoader;
 use anyhow::Context;
 use ddddocr_core::error::{DdddError, Result};
 use ddddocr_core::{DetEngine, DetOutput, InferenceEngine};
@@ -10,15 +10,6 @@ pub struct DetSession {
     pub session: RunnableModel<TypedFact, Box<dyn TypedOp>, Graph<TypedFact, Box<dyn TypedOp>>>,
 }
 
-impl ModelSession for DetSession {
-    fn get_model_type(&self) -> ModelType {
-        todo!()
-    }
-    fn desc(&self) -> String {
-        "Detection Model 加载成功".to_string()
-    }
-}
-
 impl DetSession {
     pub fn new<P>(model_path: P) -> Result<Self>
     where