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>

pyproject.toml

@@ -23,6 +23,9 @@ server = [
 cv = [
     "opencv-python>=4.8.0",
 ]
+dev = [
+    "pytest>=7.0.0",
+]
 
 [project.scripts]
 captcha = "cli:main"