Fix signature field formatting and add text truncation

Address customer feedback on signature field layout issues:
- Added truncation logic in `PDFBurner.vb` to limit text length
  based on per-field maximums, appending a suffix (e.g., `..`).
- Enhanced `PDFBurnerParams.vb` with `TextMaxLengths` and
  `TruncationSuffix` for configurable truncation behavior.
- Improved spacing and layout handling for signature fields to
  prevent text collisions within fixed dimensions.
- Updated `EnvelopeGenerator.sln` with documentation for the
  signature formatting fix (`fix-signature-field-formatting.md`).
- Applied truncation consistently across `AddFormFieldValue`
  overloads and ensured deterministic rendering of annotations.

fix-signature-field-formatting.md

@@ -0,0 +1,111 @@
+# Signature Field Formatting — WISAG Feedback
+
+## Context
+
+Customer feedback received from the new WISAG signFLOW project lead (email dated 3/7/2026).  
+The signature stamp rendered inside the finalized PDF has layout issues that need to be addressed.
+
+### Current State (screenshot from customer email)
+
+```
+Signiert von ___________
+[ signature image       ]
+Armin Schneider
+C6B85E96A520C60...       ← certificate hash, too close to name
+Bereichsleiter Kern-     ← position text wraps, no spacing to date
+Anwendungen
+Frankfurt am Main
+23.06.2026, 17:13:42 GMT+2
+```
+
+### Issues Reported
+
+1. **Spacing between name and certificate number** is too small — needs more vertical gap.
+2. **Spacing between position/title and date/time** is too small — should be dynamic (expand with content).
+3. *(Secondary, out of scope here)* Multiple signature fields side-by-side scale individually, causing uneven heights.
+
+---
+
+## Agreed Solution
+
+> **"Height stays fixed. Text stretches horizontally. Beyond a certain character limit, truncate with '...'"**  
+> *(Original: "Höhe bleibt fix. Text dehnt sich horizontal aus. Ab einem bestimmten Limit wird mit '...' abgekürzt.")*
+
+### Rationale
+
+- The signature field dimensions are **fixed** (`1.77" × 1.96"`). Allowing text to wrap causes position and date rows to collide vertically.
+- Truncating long strings with ellipsis (`...`) keeps the layout deterministic and prevents overflow.
+- Per-field max-length limits allow tuning each text row independently (name, certificate, position, city, date).
+
+---
+
+## Implementation Plan
+
+### 1. `PDFBurnerParams.vb` — Add per-field max-length dictionary
+
+Add a new property `TextMaxLengths` that maps each field name (matching `EGName` keys) to a maximum character count.
+
+```vbnet
+' EnvelopeGenerator.CommonServices/Jobs/FinalizeDocument/PDFBurnerParams.vb
+
+Public Property TextMaxLengths As New Dictionary(Of String, Integer) From {
+    {"name",      28},
+    {"position",  32},
+    {"city",      24},
+    {"date",      28}
+}
+```
+
+Default values are starting points and should be tuned against real customer data.
+
+### 2. `PDFBurner.vb` — Add truncation helper and apply in `AddFormFieldValue`
+
+#### 2a. Add a private helper function
+
+```vbnet
+Private Function TruncateText(value As String, fieldName As String) As String
+    If String.IsNullOrEmpty(value) Then Return value
+
+    Dim maxLen As Integer = 0
+    If _pdfBurnerParams.TextMaxLengths IsNot Nothing AndAlso
+       _pdfBurnerParams.TextMaxLengths.TryGetValue(fieldName, maxLen) AndAlso
+       maxLen > 0 AndAlso value.Length > maxLen Then
+        Return value.Substring(0, maxLen - 3) & "..."
+    End If
+
+    Return value
+End Function
+```
+
+#### 2b. Apply truncation in the `egName`-aware overload
+
+In `AddFormFieldValue(pAnnotation As Annotation, formFieldValue As FormFieldValue)`:
+
+```vbnet
+' Before passing value to AddTextAnnot, truncate:
+Dim displayValue As String = TruncateText(formFieldValue.value, pAnnotation.egName)
+
+Dim ant = Manager.AddTextAnnot(oX, oY, oWidth, oHeight, displayValue)
+```
+
+#### 2c. Apply truncation in the element-based overload (optional)
+
+In `AddFormFieldValue(x, y, width, height, page, value)` — if a field name is available in calling context, pass it through; otherwise this path does not use `egName` and truncation can be skipped or applied with a generic fallback key.
+
+---
+
+## Affected Files
+
+| File | Change |
+|------|--------|
+| `EnvelopeGenerator.CommonServices/Jobs/FinalizeDocument/PDFBurnerParams.vb` | Add `TextMaxLengths As Dictionary(Of String, Integer)` |
+| `EnvelopeGenerator.CommonServices/Jobs/FinalizeDocument/PDFBurner.vb` | Add `TruncateText()` helper; apply in `AddFormFieldValue` overloads |
+
+---
+
+## Notes
+
+- Field names (`"name"`, `"position"`, `"city"`, `"date"`) must match the keys used in `EGName.Index` dictionary (`PDFBurner.vb:443–450`).
+- The certificate hash field (e.g. `C6B85E96A520C60...`) is already truncated upstream — verify its `egName` mapping if it needs its own limit.
+- The `YOffset` / `TopMargin` values in `PDFBurnerParams` may also need adjustment to increase vertical spacing between rows. That is a separate (simpler) change.
+- This issue is **not** related to the Blazor WebUI rendering — it is purely in the GdPicture14 PDF burning pipeline.