docs: add FastVideo FastH3 fast generation guide for MiniMax H3

[lin-bot23]

workflow_templates v0.11.61/v0.11.62 (Comfy-Org/workflow_templates#1264, #1265) added two FastVideo FastH3 templates for MiniMax H3: video_fastvideo_fasth3_t2v and video_fastvideo_fasth3_i2v (openSource, minComfyUIVersion 0.36.0).

This adds a new tutorial page tutorials/video/minimax/minimax-h3-fastvideo.mdx covering:

• What FastH3 is: a DMD2-distilled MiniMax H3 checkpoint generating synchronized video and audio in 8 sampling steps, reusing the H3 text encoder and VAEs
• Scope note: t2va and fl2va only, Ref2VA was not distilled
• Both workflows with previews, download cards, prompting tips, and input material
• Model downloads (FastVideo diffusion model + shared H3 text encoder/VAEs) and storage tree
• Workflow structure notes (BlockSparseAttention VSA settings, MiniMaxH3SigmaShift, 17k+5 frame grid)

Nav entries added to the MiniMax H3 group in all 4 languages. Comfy Cloud cards are commented out until the templates are available in Comfy Cloud.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Advanced

Run ID: bd83849a-dd7e-4ac5-86e6-18a808ee93b3

📥 Commits

Reviewing files that changed from the base of the PR and between c469616 and 434f993.

📒 Files selected for processing (4)

• ja/tutorials/video/minimax/minimax-h3-fastvideo.mdx
• ko/tutorials/video/minimax/minimax-h3-fastvideo.mdx
• tutorials/video/minimax/minimax-h3-fastvideo.mdx
• zh/tutorials/video/minimax/minimax-h3-fastvideo.mdx

Included review availability: Your plan provides up to 2 included reviews per hour; 1 remains after this review.

---

📝 Walkthrough

Walkthrough

FastH3 documentation was added in English, Japanese, Chinese, and Korean. The pages describe text-to-video and first/last-frame image-to-video workflows, model setup, prompt guidance, and workflow settings. Navigation now links to the new pages.

Changes

MiniMax H3 FastVideo Documentation

Layer / File(s)	Summary
English FastH3 tutorial tutorials/video/minimax/minimax-h3-fastvideo.mdx	Added FastH3 text-to-video and first/last-frame image-to-video workflows, model downloads, prompt guidance, and workflow settings.
Localized FastH3 tutorials ja/tutorials/video/minimax/minimax-h3-fastvideo.mdx, zh/tutorials/video/minimax/minimax-h3-fastvideo.mdx, ko/tutorials/video/minimax/minimax-h3-fastvideo.mdx	Added Japanese, Chinese, and Korean translations of the FastH3 tutorial.
Multilingual tutorial navigation docs.json	Added the tutorial to the English, Chinese, Japanese, and Korean MiniMax H3 navigation lists.

Priority: ⬇️ Low

Merge Risk: ⚪ Minimal · up to 434f9

The PR adds the FastH3 documentation and multilingual navigation without an identified merge-blocking risk.

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

✨ Simplify code

• Create PR with simplified code

---

_{Comment @coderabbitai help to get the list of available commands.}