docs(agents): forbid self-claiming and unverified detail embedding

[iap]

Adds a guideline to AGENTS.md:

• Avoid self-claiming and embedding unverified detail. Never claim you verified something you did not.
• Do not over-specify routine conventions in comments (e.g. tagging a commit as "GPG-signed" when the repo requires signing by default).
• State only what you did and observed.

This addresses a recurring issue: commit messages/PR bodies claiming verification steps (like signing status) as if they were novel or explicitly performed, when they are actually the baseline state. Keeps claims evidence-grounded.

Greptile Summary

This change adds guidance for accurate agent reporting and adds CI linting for GitHub Actions workflows. The actionlint job was exercised using its exact release URL, checksum, extraction command, and no-argument invocation: the archive checksum passed, version 1.7.12 ran successfully, and workflow discovery correctly identified an intentionally invalid control workflow.

Confidence Score: 5/5

Safe to merge based on the verified workflow behavior and absence of reported defects.

The changed CI path was reproduced end to end, including download integrity verification, extraction, workflow linting, and a control proving that no-argument invocation discovers workflow files.

Files Needing Attention: No files need follow-up changes.

T-Rex Logs

What T-Rex did

• Validated the actionlint workflow by performing the exact archive download, checksum verification, extraction, and a no-argument actionlint run; the archive check was OK, the binary reported version 1.7.12, and both explicit lint and no-argument lint exited successfully, with a no-argument discovery detecting an invalid workflow to prove directory discovery works.
• Explicit lint of the CI workflow file and a no-argument actionlint run both exited with code 0, and a no-argument discovery control confirmed that directory discovery occurs.
• Created and used a focused actionlint workflow validation script to drive theChecks and capture validation evidence.

_{Ran code and verified through T-Rex}

_{Reviews (1): Last reviewed commit: "docs(agents): forbid self-claiming and u..." | Re-trigger Greptile}