[api] Use multiply instead of loop for constant-size repeated enums

When a repeated enum field has a constant size per element (max < 128),
emit size * constant instead of iterating. This fixes unused variable
warnings from clang-tidy and generates more efficient code.

script/api_protobuf/api_protobuf.py

@@ -1907,17 +1907,27 @@ class RepeatedTypeInfo(TypeInfo):
             size_expr = f"{name}->size()" if self._use_pointer else f"{name}.size()"
             o += f"  size += {size_expr} * {bytes_per_element};\n"
         else:
-            # Other types need the actual value
+            # Check if inner type produces a constant size (doesn't depend on value)
+            inner_size = self._ti.get_size_calculation("it", True)
+            if "it" not in inner_size:
+                # Constant size per element — use multiply instead of loop
+                # Extract the constant from "size += N;"
+                const_val = (
+                    inner_size.strip().removeprefix("size += ").removesuffix(";")
+                )
+                size_expr = f"{name}->size()" if self._use_pointer else f"{name}.size()"
+                o += f"  size += {size_expr} * {const_val};\n"
             # Special handling for const char* elements
-            if self._use_pointer and "const char" in self._container_no_template:
+            elif self._use_pointer and "const char" in self._container_no_template:
                 field_id_size = self.calculate_field_id_size()
                 o += f"  for (const char *it : {container_ref}) {{\n"
                 o += f"    size += ProtoSize::calc_length_force({field_id_size}, strlen(it));\n"
+                o += "  }\n"
             else:
                 auto_ref = "" if self._ti_is_bool else "&"
                 o += f"  for (const auto {auto_ref}it : {container_ref}) {{\n"
-                o += f"    {self._ti.get_size_calculation('it', True)}\n"
-            o += "  }\n"
+                o += f"    {inner_size}\n"
+                o += "  }\n"
 
         o += "}"
         return o