[Kandinsky 5] Fix I2V conditioning: don't inject the image latent into visual_cond channels (#14282)
Fix Kandinsky 5 I2V: don't duplicate image latent into visual_cond channels
Kandinsky5I2VPipeline.prepare_latents injected the conditioning image both as the
first latent frame and into the visual_cond channels; the reference implementation
(kandinskylab/kandinsky-5) only does the former. The duplicate over-conditions the
first frame and produces mesh/visual artifacts. Remove the redundant injection to
match the reference.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>