Goal: add documentation to readme reflecting Claude and Codex's use of /goal

## Goal

Our readme should contain references to the use of `/goal` in Claude Code and Codex, with appropriate links. Not extended discussion, but we want to note that we are using this now-standard term.

We also want to make sure we link to https://github.com/githubnext/autoloop which also inspired this repo. Autoloop is a similar goal-driven agentic workflow, with more of an emphasis on scientific exploration.

## Completion Contract

The README.md "Built On" section (or a similar appropriate section) links to:
- Claude Code `/goal` documentation
- Codex `/goal` documentation
- https://github.com/githubnext/autoloop with a brief description

## Evidence / Verification

```bash
set -euo pipefail
grep -q "autoloop" README.md
grep -qi "claude" README.md
grep -qi "codex" README.md
grep -q "https://github.com/githubnext/autoloop" README.md
```

All commands must exit 0.

## Scope and Constraints

Allowed files:
- `README.md`

Do not remove existing content. Keep additions brief — a few lines, not paragraphs.

## Iteration Policy

This is a single-run goal. Read the current README, add the references, and verify.

## Blocked Stop Condition

If the official `/goal` documentation URLs for Claude Code or Codex cannot be found or confirmed, add placeholder references noting the feature and stop with a comment listing which URLs need human confirmation.