Add xlsxwriter-based Excel generation scripts with openpyxl implementation

- Created create_excel_xlsxwriter.py and update_excel_xlsxwriter.py
- Uses openpyxl exclusively to preserve Excel formatting and formulas
- Updated server.js to use new xlsxwriter scripts for form submissions
- Maintains all original functionality while ensuring proper Excel file handling

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

venv/lib/python3.12/site-packages/openpyxl/packaging/interface.py

@@ -0,0 +1,56 @@
+# Copyright (c) 2010-2024 openpyxl
+
+from abc import abstractproperty
+from openpyxl.compat.abc import ABC
+
+
+class ISerialisableFile(ABC):
+
+    """
+    Interface for Serialisable classes that represent files in the archive
+    """
+
+
+    @abstractproperty
+    def id(self):
+        """
+        Object id making it unique
+        """
+        pass
+
+
+    @abstractproperty
+    def _path(self):
+        """
+        File path in the archive
+        """
+        pass
+
+
+    @abstractproperty
+    def _namespace(self):
+        """
+        Qualified namespace when serialised
+        """
+        pass
+
+
+    @abstractproperty
+    def _type(self):
+        """
+        The content type for the manifest
+        """
+
+
+    @abstractproperty
+    def _rel_type(self):
+        """
+        The content type for relationships
+        """
+
+
+    @abstractproperty
+    def _rel_id(self):
+        """
+        Links object with parent
+        """