refactor(pdfburner): simplify form field handling and improve default field naming

- Replaced ImmutableDictionary-based FormFieldIndex with a simpler Dictionary
- Updated form field ordering to: NoName, signature, position, city, date
- Removed manual formFieldIndex counter, now using dictionary lookup by fieldName
- Introduced FieldNames class with NoName constant (guid-based) for unnamed fields
- Defaulted Annotation.fieldName to FieldNames.NoName instead of Nothing

EnvelopeGenerator.CommonServices/Jobs/FinalizeDocument/PDFBurner.vb

@@ -69,17 +69,13 @@ Namespace Jobs.FinalizeDocument
             End Using
         End Function
 
-        Public Shared ReadOnly FormFieldIndex As ImmutableDictionary(Of String, Integer) =
-            New Dictionary(Of String, Integer) From {
-                {Nothing, 0},
-                {"signature", 0},
-                {"date", 1},
-                {"date_label", 2},
+        Public Shared ReadOnly FormFieldIndex As New Dictionary(Of String, Integer) From {
+                {FieldNames.NoName, 0},
+                {"signature", 1},
+                {"position", 2},
                 {"city", 3},
-                {"city_label", 4},
-                {"position", 5},
-                {"position_label", 6}
-            }.ToImmutableDictionary()
+                {"date", 4}
+            }
 
         Private Sub AddInstantJSONAnnotationToPDF(pInstantJSON As String)
             Dim oAnnotationData = JsonConvert.DeserializeObject(Of AnnotationData)(pInstantJSON)
@@ -88,7 +84,6 @@ Namespace Jobs.FinalizeDocument
             Dim yPosOfSigAnnot = oAnnotationData.annotations.ElementAt(2).bbox.ElementAt(1) - 71.84002685546875 + 7
             Dim isSeal = True   'First element is signature seal
 
-            Dim formFieldIndex = 0
             For Each oAnnotation In oAnnotationData.annotations
                 Logger.Debug("Adding AnnotationID: " + oAnnotation.id)
 
@@ -110,8 +105,7 @@ Namespace Jobs.FinalizeDocument
                         'Add form field values
                         Dim formFieldValue = oAnnotationData.formFieldValues.FirstOrDefault(Function(fv) fv.name = oAnnotation.id)
                         If formFieldValue IsNot Nothing AndAlso Not _pdfBurnerParams.IgnoredLabels.Contains(formFieldValue.value) Then
-                            AddFormFieldValue(oAnnotation, formFieldValue, formFieldIndex)
-                            formFieldIndex += 1
+                            AddFormFieldValue(oAnnotation, formFieldValue)
                         End If
                         Exit Select
                 End Select
@@ -152,12 +146,15 @@ Namespace Jobs.FinalizeDocument
             Next
         End Function
 
-        Private Function AddFormFieldValue(pAnnotation As Annotation, formFieldValue As FormFieldValue, index As Integer) As Void
+        Private Function AddFormFieldValue(pAnnotation As Annotation, formFieldValue As FormFieldValue) As Void
+
+            Dim index As Integer = FormFieldIndex(pAnnotation.fieldName)
+
             ' Convert pixels to Inches
             Dim oBounds = pAnnotation.bbox.Select(AddressOf ToInches).ToList()
 
             Dim oX = oBounds.Item(0)
-            Dim oY = oBounds.Item(1) + _pdfBurnerParams.YOffset * index + _pdfBurnerParams.TopMargin
+            Dim oY = oBounds.Item(1) + _pdfBurnerParams.YOffset * Index + _pdfBurnerParams.TopMargin
             Dim oWidth = oBounds.Item(2)
             Dim oHeight = oBounds.Item(3)
 
@@ -220,7 +217,7 @@ Namespace Jobs.FinalizeDocument
 
             Public index As Integer = Nothing
 
-            Public fieldName As String = Nothing
+            Public fieldName As String = FieldNames.NoName
 
             Public hasStructuredID As Boolean = False
 
@@ -286,6 +283,10 @@ Namespace Jobs.FinalizeDocument
             Public Property strokeColor As String
         End Class
 
+        Public Class FieldNames
+            Public Shared ReadOnly NoName As String = Guid.NewGuid().ToString()
+        End Class
+
         Friend Class Lines
             Public Property points As List(Of List(Of List(Of Single)))
         End Class