python/v0.2.3

Added

• Add Kling 2.6 text-to-video and image-to-video constraints to shared contract metadata.
• Add generated validation metadata for Midjourney first-video extension requests.
• Add generated validation metadata for Flux text-to-image and remix-image requests.
• Publish Veo 3.1 Lite model and input constraints in aggregate contract metadata.
• Add shared request validation metadata for Qwen Image generation, remix, and edit endpoints.