Use placeholders instead of tokens

src/main/proto/spine/options.proto

@@ -885,7 +885,7 @@ message GoesOption {
 
     // The default error message used when the companion field specified in `with` is not present
     // alongside the target field.
-    option (default_message) = "The field `%s` can only be set when the field `%s` is defined.";
+    option (default_message) = "The field `{fieldName}` can only be set when `{companionName}` field is defined.";
 
     // The name of the companion field whose presence is required for this field to be valid.
     string with = 1;
@@ -895,7 +895,7 @@ message GoesOption {
 
     // A user-defined error message.
     //
-    // The specified message may include the following tokens:
+    // The specified message may include the following placeholders:
     // 1. `{fieldName}` – the name of the field to which this option is applied.
     // 2. `{companionName}` – the name of the companion field specified in `with`.
     //
@@ -1077,12 +1077,12 @@ message IfSetAgainOption {
 
     // A user-defined error message.
     //
-    // The specified message may include the following tokens:
+    // The specified message may include the following placeholders:
     // 1. `{fieldName}` — the field name.
     // 2. `{currentValue}` — the current field value.
     // 3. `{proposedValue}` — the value that was attempted to be set.
     //
-    // The tokens will be replaced at runtime when the error is constructed.
+    // The placeholders will be replaced at runtime when the error is constructed.
     //
     // Example: Using the `(set_once)` option.
     //