… Base, and fix metadata recall

Klein 4B and 9B (distilled) have guidance_embeds=False, while Klein 9B Base
(undistilled) has guidance_embeds=True. This commit:
- Sets guidance_embed=False for Klein 4B/9B and adds Klein9BBase with True
- Adds guidance parameter to Flux2DenoiseInvocation (used by Klein 9B Base)
- Passes real guidance value instead of hardcoded 1.0 in flux2/denoise.py
- Hides guidance slider for distilled Klein models, shows it for Klein 9B Base
- Shows Flux scheduler dropdown for all Flux2 Klein models
- Passes scheduler to Flux2 denoise node and saves it in metadata
- Adds KleinVAEModel and KleinQwen3EncoderModel to recall parameters panel