Add tests, server, resume training, and project cleanup

- Add 57 unit tests covering generators, models, and pipeline components
- Implement FastAPI HTTP service (server.py) with POST /solve and GET /health
- Add checkpoint resume (断点续训) to both CTC and regression training utils
- Fix device mismatch bug in CTC training (targets/input_lengths on GPU)
- Add pytest dev dependency to pyproject.toml
- Update .gitignore with data/solver/, data/real/, *.log
- Remove PyCharm template main.py
- Update training/__init__.py docs for solver training scripts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

training/__init__.py

@@ -10,4 +10,6 @@
 - train_3d_rotate.py:        训练 3D 旋转回归 (RegressionCNN)
 - train_3d_slider.py:        训练 3D 滑块回归 (RegressionCNN)
 - train_classifier.py:       训练调度分类器 (CaptchaClassifier)
+- train_slide.py:            训练滑块缺口检测 (GapDetectorCNN)
+- train_rotate_solver.py:    训练旋转角度回归 (RotationRegressor)
 """