feat(wafer): introduce layout metadata modeling and shape resolution helpers

- Define WaferLayout subclass to wrap sensor lists with shape and size attributes.
- Add resolve_shape_and_size resolver to infer wafer shape/size from filename prefix or sensor count.
- Update Sensor dataclass to support dynamic side alignments and coordinates offsets.
- Expose waferShape and waferSize properties from SessionController for QML data-bindings.

src/pygui/backend/data/csv_file_metadata.py

@@ -25,8 +25,8 @@ class CSVFileMetadata:
         try:
             return datetime.strptime(self.date, date_format)
         except (ValueError, TypeError):
-            # If format is wrong or date is None, return current time
-            return datetime.now()
+            # If format is wrong or date is None, return None
+            return None
 
     # ===== Formatting =====
     @staticmethod
@@ -48,4 +48,5 @@ class CSVFileMetadata:
 
     def string_date_format(self) -> str:
         """Helper to ensure the date is always a string for JSON."""
-        return self.format_date(self.get_date())
+        dt = self.get_date()
+        return self.format_date(dt) if dt else self.date