docs: add rectified flow mia artifact gate

[DeliciousBuding]

Summary

• Add a Rectified Flow / Flow Matching MIA artifact gate for arXiv 2603.13421.
• Record the mechanism as non-duplicate but paper-source-only because the promised GitHub repo is empty.
• Sync Research ROADMAP, AGENTS, evidence index, intake note, and challenger queue to keep active slots at none.

Verification

• git diff --check
• python -X utf8 scripts/check_public_surface.py
• python -X utf8 scripts/check_markdown_links.py
• python -X utf8 scripts/run_pr_checks.py

[gemini-code-assist]

Code Review

This pull request documents the 'Rectified Flow MIA Artifact Gate' following an investigation into arXiv 2603.13421. The changes update the roadmap, status reports, and evidence indices to reflect that while the paper introduces a non-duplicate MIA mechanism for Rectified Flow models, the associated GitHub repository is currently empty, resulting in a 'mechanism watch' status with no active resource allocation. Feedback was provided to correct a duplicated chronological label in the evidence index to ensure a consistent descending sequence.

[gemini-code-assist]

The label "Earlier Research update:" is duplicated here. It should follow the descending chronological sequence (Latest -> Previous -> Earlier -> Prior -> Older) as established in the preceding sections of this file.

Suggested change

	Earlier Research update:
	Older Research update:

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