docs: add VISION + contributor handoff docs (EPIC-6/7)

[100yenadmin]

Adds VISION.md (product framing, incl. the client/server boundary vs
evaos-cortex) and AGENTS.md (contributor/agent guide) so a future agent
handed this repo alone can carry it forward, per the EPIC-6/7 governance
mandate.

Part of EPIC-6 #271 / EPIC-7 #272. Pure additive docs.

DO NOT MERGE — awaiting owner review across all three EPIC-6/7 repos.

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.
To continue using code reviews, add credits to your account and enable them for code reviews in your settings.

[coderabbitai]

Warning

Review limit reached

You’ve reached a temporary PR review limit under our Fair Usage Limits Policy.

Your recent review volume is higher than typical usage, so adaptive limits are currently applied.

Next review available in: 30 minutes

Enable usage-based reviews in Billing to review now. Otherwise, wait until the next included review is available.
You're only billed for reviews past your plan's rate limits ($0.25/file).

How can I continue?

After more reviews become available, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

To avoid repeated limits, reduce automatic review volume by pausing incremental auto-reviews earlier, using label-based review opt-in, excluding WIP or generated PR titles, or requesting reviews manually when the PR is ready. If your team needs uninterrupted high-volume reviews, an organization admin can enable usage-based reviews.

How do review limits work?

CodeRabbit enforces per-developer PR review limits for each organization. Most developers receive the normal plan review availability.

For paid Pro and Pro+ PR reviews, CodeRabbit uses adaptive limits for sustained high-volume activity. When a developer's recent PR review activity reaches the 95th percentile or higher among CodeRabbit users, additional reviews become available more gradually as earlier reviews age out of the rolling window.

Please refer docs for additional details.

Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: bd5b8da4-1b8f-45d4-9779-39d1cd8d7c1c

📥 Commits

Reviewing files that changed from the base of the PR and between d0812ad and 810d869.

📒 Files selected for processing (2)

• AGENTS.md
• VISION.md

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/contributor-handoff

---

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