refactor: Drop residual unused vars and SuppressWarnings

Cleans up two leftovers from the SonarQube pass: an unused Boolean
binding in SchemaParser.parseAdditionalProperties (the false branch
doesn't need the value) and a no-longer-needed @SuppressWarnings on
Spec.resolveParameterOrParse.

Author: thced

src/main/java/com/retailsvc/http/spec/Spec.java

@@ -151,7 +151,6 @@ private static Operation parseOperation(
     return new Operation(opId, method, path, body, params, responses);
   }
 
-  @SuppressWarnings("unchecked")
   private static Parameter resolveParameterOrParse(
       Map<String, Object> raw, Map<String, Parameter> componentParameters) {
     String ref = (String) raw.get("$ref");

src/main/java/com/retailsvc/http/spec/schema/SchemaParser.java

@@ -126,7 +126,7 @@ private static AdditionalProperties parseAdditionalProperties(Object value) {
     return switch (value) {
       case null -> new AdditionalProperties.Allowed();
       case Boolean b when b -> new AdditionalProperties.Allowed();
-      case Boolean b -> new AdditionalProperties.Forbidden();
+      case Boolean _ -> new AdditionalProperties.Forbidden();
       default -> new AdditionalProperties.SchemaConstraint(parse((Map<String, Object>) value));
     };
   }