fix: use brace initialization for bool to json conversion

- nlohmann_json 3.12 requires explicit construction for bool values
- Brace initialization syntax {value} works with explicit constructors
- Applied to all bool-to-json conversions in the codebase

Author: timblaktu

src/v2/pdf_resources/page_cell.h

@@ -186,15 +186,9 @@ namespace pdflib
       cell.push_back(font_name); // 18
 
       // Work around nlohmann_json 3.12 explicit bool constructor
-      {
-        nlohmann::json widget_json;
-        widget_json = widget;
-        cell.push_back(widget_json); // 19
-
-        nlohmann::json ltr_json;
-        ltr_json = left_to_right;
-        cell.push_back(ltr_json); // 20
-      }
+      // Use brace initialization to explicitly construct from bool
+      cell.push_back(nlohmann::json{widget}); // 19
+      cell.push_back(nlohmann::json{left_to_right}); // 20
     }
     assert(cell.size()==header.size());
 

src/v2/pdf_sanitators/cells.h

@@ -123,8 +123,9 @@ namespace pdflib
 
 	  item["rendering_mode"] = cell.rendering_mode;
 
-	  item["widget"] = cell.widget;
-	  item["left_to_right"] = cell.left_to_right;
+	  // Work around nlohmann_json 3.12 explicit bool constructor
+	  item["widget"] = nlohmann::json{cell.widget};
+	  item["left_to_right"] = nlohmann::json{cell.left_to_right};
 	}
 
 	result.push_back(item);

src/v2/qpdf/to_json.h

@@ -163,9 +163,8 @@ namespace pdflib
           {
             bool val = obj.getBoolValue();
             // Work around nlohmann_json 3.12 explicit bool constructor
-            // Create json and assign bool value
-            result = nlohmann::json();
-            result = val;
+            // Use brace initialization to explicitly construct from bool
+            result = nlohmann::json{val};
           }
         else
           {