[Chat] Enhancing the JSON schema with validation constraints

[wachterjohannes]

While the schema structure is good, consider adding validation constraints to improve data quality:

             new JsonSchemaResponseFormat([
                 'type' => 'object',
                 'properties' => [
                     'name' => [
                         'type' => 'string',
                         'description' => 'The name of the user',
+                        'minLength' => 1,
+                        'maxLength' => 100
                     ],
                     'age' => [
                         'type' => 'integer',
                         'description' => 'The age of the user',
+                        'minimum' => 0,
+                        'maximum' => 150
                     ],
                 ],
+                'required' => ['name', 'age'],
+                'additionalProperties' => false
             ]),

Originally generated by #112 (review)