- PdfViewerWrapper: add selectedFieldId?, textFillData?, onFieldSelect?, onFieldValueChange? and forward to PdfViewer
- PdfViewer: add same 4 optional props, forward to FieldPlacer; call onFieldSelect?.(null) on page navigation
- FieldPlacer: extend FieldPlacerProps with 4 new optional props
- DroppableZone: add optional onClick prop for background deselect
- renderFields: text fields show inline input when selected (isSelected), value/label otherwise
- Per-field onClick: text fields call onFieldSelect(id), non-text fields call onFieldSelect(null)
- Cursor updated to 'text' for text field type; boxShadow ring on selected state