feat: 导入 IRSTD 研究代码与文档（小目标检测）

- 新增 irstd 核心包、scripts、tests、configs
- 新增研究文档：literature_review / mathematical_analysis / novelty_matrix / experiment_plan / research_decision / research_log / manuscript_outline
- 新增 evidence、results 数据与审计产物
- 新增 pyproject.toml、requirements、.gitignore

data/README.md

@@ -0,0 +1,15 @@
+# Dataset contract
+
+No real dataset is bundled. Verify original download terms before use. Create a CSV:
+
+```csv
+id,image,mask,split,group
+example_train,images/example_train.png,masks/example_train.png,train,scene_a
+example_dev,images/example_dev.png,masks/example_dev.png,dev,scene_b
+example_cal,images/example_cal.png,masks/example_cal.png,cal,scene_c
+example_test,images/example_test.png,masks/example_test.png,test,scene_d
+```
+
+These are format examples, not real files. Paths resolve relative to the CSV. Input is 2D uint8 grayscale, masks are same-sized 2D arrays with zero background and positive foreground. Conversion from 16-bit data requires an explicit versioned preprocessing procedure; the loader refuses silent conversion. Preserve native coordinates. Scene groups must not cross splits. Group fields cannot establish independence by themselves.
+
+Keep dataset source URL, downloaded archive SHA256, actual license text, upstream split hashes, conversion settings and annotation-audit findings beside the private data. Do not redistribute datasets with this repository until rights are established.