style: standardize VBA property and method name casing

Standardize all VBA property and method names to lowercase for consistent code style:
- Err object: Err.Description → err.Description, Err.Number → err.Number
- Collection properties: .Count → .count
- Range properties: .Rows.Count → .Rows.count, .Row → .row
- Dictionary methods: .Keys → .keys, .Exists → .exists
- Worksheet properties: .Sheets.Count → .Sheets.count
- Fix typo: Thisworkbook.Path → ThisWorkbook.Path

VBA is case-insensitive, but consistent lowercase convention improves readability.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

VBA_BOMConverter/Modules/M06_ModelParser.bas

@@ -161,7 +161,7 @@ Public Function ParseProductModel(ByVal modelString As String) As Object
 ErrorHandler:
     If Not g_Logger Is Nothing Then
         g_Logger.Record "", "M06.ParseProductModel", "SystemError", _
-            "解析过程发生错误: " & Err.Description, modelString
+            "解析过程发生错误: " & err.Description, modelString
     End If
     Set ParseProductModel = CreateObject("Scripting.Dictionary")
 End Function