Add initial backend structure with models, utilities, and settings management

- Introduced .gitignore to exclude common Python artifacts and IDE files.
- Added contour models for contour generation.
- Implemented cryptographic utilities for data encryption and decryption.
- Created CSV metadata model for handling wafer data.
- Developed time-indexed data segment model.
- Established local settings model for application configuration.
- Added Z-wafer data models and parser for CSV file handling.
- Implemented Marching Squares algorithm for contour generation.

.gitignore

@@ -0,0 +1,30 @@
+# Python
+__pycache__/
+*.pyc
+*.pyo
+*.pyd
+*.so
+*.a
+
+# Virtual environment
+.venv/
+venv/
+env/
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Qt / QML cache
+Qt/
+qrc_*.cpp
+moc_*.cpp
+*.qmlcache
+*.qmldir.cache