feat: add extraction_service (PDF/Docx/Txt) and update .gitignore to exclude venv

.gitignore

@@ -48,6 +48,78 @@ tmp/
 temp/
 *.tmp
 
+# ==================== Python ====================
+# Virtual environments (重要！避免提交 2+ GB 的依赖)
+venv/
+env/
+.venv/
+ENV/
+env.bak/
+venv.bak/
 
+# Python cache
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
 
+# PyInstaller
+*.manifest
+*.spec
 
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# pyenv
+.python-version
+
+# Celery
+celerybeat-schedule
+celerybeat.pid
+
+# Environments
+.env
+.venv
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+
+# Unit test / coverage
+htmlcov/
+.tox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre
+.pyre/
+
+# pytype
+.pytype/
+
+# Cython
+cython_debug/