feat: add Arcaeon llms.txt

[dan8433-user]

Adds an entry for Arcaeon (https://arcaeon.io), which serves both /llms.txt and /llms-full.txt (verified live 2026-08-14). Arcaeon builds small, honest, verifiable tools for the agent economy: tamper-evident action logs (arcaeon-ledger, PyPI), audit exports, and a hosted external witness service. Category set to security-identity per the existing taxonomy. Follows the manual-PR path in CONTRIBUTING.md (new .mdx file under packages/content/data/websites/, data/websites.json left untouched since it's auto-generated).

Summary by CodeRabbit

• New Features
  • Added an Arcaeon website entry with publication details, relevant links, and a product description.
  • Included information about Arcaeon’s agent-focused tools, tamper-evident action logs, external verification, review history, and disclosure policy.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: da99bde9-8b41-4bde-909f-e15e00fe5e48

📥 Commits

Reviewing files that changed from the base of the PR and between 0e9cd30 and b3b19d3.

📒 Files selected for processing (1)

• packages/content/data/websites/arcaeon-llms-txt.mdx

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Walkthrough

Added an Arcaeon website entry with metadata, LLM documentation links, publication information, and descriptions of its ledger and non-proof policy.

Changes

Arcaeon content entry

Layer / File(s)	Summary
Website metadata and introductory content packages/content/data/websites/arcaeon-llms-txt.mdx	Adds Arcaeon metadata, website links, publication date, category, ledger description, and introductory content.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to b3b19

This change adds one localized Arcaeon directory entry without altering generated data or runtime behavior, so no actionable merge-blocking risk remains beyond normal checks and review.

Possibly related PRs

• thedaviddias/llms-txt-hub#1426: Adds a similarly structured website entry.
• thedaviddias/llms-txt-hub#1439: Adds an MDX website entry with the same metadata and content pattern.
• thedaviddias/llms-txt-hub#1463: Adds an agent-infrastructure website entry under the same content directory.

Suggested labels: lane:mdx-fast, risk:low

Suggested reviewers: thedaviddias

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description clearly summarizes the Arcaeon entry and confirms the required .mdx path and unchanged auto-generated file.
Title check	✅ Passed	The title clearly identifies the primary change: adding an Arcaeon llms.txt entry.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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

Warning

Review ran into problems

🔥 Problems

These MCP integrations need to be re-authenticated in the Integrations settings: Sentry

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