Drop copied GPU validation paragraph from AGENTS.md

[avifenesh]

The "Validation scope" section at the end of AGENTS.md talks about GPU, native and model qualification gates. It was pasted in from another project. This repo holds research guides and has no GPU or model behavior, so the section is removed.

Checks

• agnix . (v0.56.5): 0 errors, 0 warnings.
• No package.json, so the node CI job has no tests to run here.

[avifenesh]

Self-review (fresh-context subagent)

No blocking findings.

Checked:

• The removed "Validation scope" section is generic GPU, native and model qualification text. AGENTS.md here is a topic index with no repo rules, so nothing repo-specific is lost. No other copy of the text exists in the repo.
• The file now ends cleanly after the "How to Use" list (AGENTS.md:760-765). No trailing blank line left behind.
• CI: ci / test and agnix / agnix pass. claude-review is skipped, not failed. Diff is AGENTS.md only (9 deletions).
• The two guides that agent-analyzer#44 links (ai-commit-detection-forensics.md, git-history-analysis-developer-tools.md) exist at the repo root on main, so that link fix resolves against this repo.