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.

backend/local_settings.py

@@ -0,0 +1,93 @@
+import json
+import os
+from pathlib import Path
+
+
+# ===== Settings Persistence Model =====
+class LocalSettings:
+    # ===== Defaults =====
+    def __init__(self):
+        self.chamber_id = ""
+        self.reverse_z_wafer = False
+        self.master = {}  # Dict[str, str]
+        self.wafer_data_size = {}  # Dict[str, int]
+        self.debug = False
+        self.wafer_read_retries = 8
+        # Timeout in msec for reading from the wafer (default 2 min)
+        self.wafer_read_timeout = 120000
+        self.wafer_detect_timeout = 5000
+        self.split_threshold = 40.0
+
+    # ===== File Path Helpers =====
+    @classmethod
+    def _settings_path(cls, directory: str) -> Path:
+        return Path(directory) / "settings.json"
+
+    # ===== Load/Save =====
+    @classmethod
+    def read_settings(cls, directory: str) -> "LocalSettings":
+        """Read settings from settings.json in the provided directory."""
+        settings = cls()
+        path = cls._settings_path(directory)
+
+        if not path.exists():
+            return settings
+
+        try:
+            with open(path, "r", encoding="utf-8") as f:
+                data = json.load(f)
+            for key, value in data.items():
+                if hasattr(settings, key):
+                    setattr(settings, key, value)
+        except Exception as e:
+            print(f"Error reading setting file: {e}")
+
+        return settings
+
+    @classmethod
+    def save_settings(cls, directory: str, settings: "LocalSettings") -> None:
+        """Save the current settings instance to settings.json."""
+        path = cls._settings_path(directory)
+        path.parent.mkdir(parents=True, exist_ok=True)
+        data = settings.__dict__.copy()
+
+        try:
+            with open(path, "w", encoding="utf-8") as f:
+                json.dump(data, f, indent=4)
+        except Exception as e:
+            print(f"Error saving settings: {e}")
+
+    # ===== Master File Helpers =====
+    @classmethod
+    def get_master(cls, directory: str, wtype: str) -> str:
+        """Return the full path to a master file if it exists."""
+        settings = cls.read_settings(directory)
+        if wtype not in settings.master:
+            return ""
+
+        file_path = Path(directory) / settings.master[wtype]
+        if file_path.exists():
+            return str(file_path)
+        return ""
+
+    @classmethod
+    def set_master(cls, directory: str, wtype: str, filename: str) -> None:
+        """Store a master filename for a wafer type and save settings."""
+        settings = cls.read_settings(directory)
+        settings.master[wtype] = os.path.basename(filename)
+        cls.save_settings(directory, settings)
+
+    # ===== Wafer Sizing =====
+    def get_wafer_data_size(self, wtype: str) -> int:
+        """Return the expected transfer size in bytes for a wafer type."""
+        if not wtype:
+            return 393216
+
+        if wtype in self.wafer_data_size:
+            return self.wafer_data_size[wtype]
+
+        if wtype == "P":
+            return 393216
+        if wtype == "X":
+            return 1310720
+        return 393216