Generalizes the i2v-anchor blur (_alg_blur_video_frame0 -> _alg_blur_frames)
to optionally also blur newly-appended guide-attention frames each scene
(mid_scene_guide / carry_i2v_guides-as-guide / configured guides / JoyAI
memory), reusing the existing guide_tail bookkeeping rather than a mask-value
heuristic (frame_overlap continuation also uses mask=0 and must stay
untouched). New Scene Chain Sampler toggle "Blur i2v guides and JoyAI memory"
mutates the shared KSAMPLER's extra_options per-chunk since guide_tail varies
per scene; always resets so nothing leaks across chunks/samplers. Surfaced in
Engine Settings via the existing Experimental section, no backend/builder
changes needed beyond the new INPUT_TYPES field.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
