refactor(core): 提炼公共类型

- 将 AxisDim、TensorInfo 等公共类型下沉至 ddddocr_core::types
- 项目结构优化

ddddocr-core/src/traits.rs

@@ -0,0 +1,42 @@
+use crate::error::TensorError;
+use crate::types::{ModelInfo, TensorInfo};
+use crate::{DetOutput, ModelMetadata, OcrOutput};
+use std::path::Path;
+
+
+pub trait Info {
+    fn input_info(&self) -> crate::error::Result<Vec<TensorInfo>>;
+    fn output_info(&self) -> crate::error::Result<Vec<TensorInfo>>;
+    fn model_info(&self) -> crate::error::Result<ModelInfo>;
+}
+
+/// 核心层定义的统一推理引擎接口。
+/// 未来的 ddddocr-tract 和 ddddocr-ort 都必须实现这个 Trait
+pub trait InferenceEngine {
+    /// 关联类型：具体的 Session 需要声明自己到底产出什么枚举
+    type Output;
+    fn inference(
+        &self,
+        input_array: ndarray::Array4<f32>,
+    ) -> crate::error::Result<Self::Output, TensorError>;
+}
+
+pub trait OcrEngine: InferenceEngine<Output = OcrOutput> + Info {
+    fn metadata(&self) -> &ModelMetadata;
+}
+
+pub trait DetEngine: InferenceEngine<Output = DetOutput> {}
+
+pub trait Loader {
+    type Session;
+    type Error;
+    fn build_for_path<P: AsRef<Path>>(
+        &self,
+        model_path: P,
+    ) -> crate::error::Result<Self::Session, Self::Error>;
+
+    fn build_from_bytes(
+        &self,
+        model_bytes: &[u8],
+    ) -> crate::error::Result<Self::Session, Self::Error>;
+}