Add GitAgent Protocol support (agent.yaml + SOUL.md)

[computer-agent]

Hi @patoles! 👋

This PR proposes adding GitAgent Protocol (GAP) support to Agent Flow — a small, open standard for portable, discoverable AI agents (https://gitagent.sh).

What this adds (nothing else changes):

• agent.yaml — a standard manifest declaring the agent name, version, model, runtime entry point, skills, and compliance tier. Modelled faithfully from your extension package.json and README.
• SOUL.md — a structured persona file describing what Agent Flow is, how it behaves, and its constraints — distilled from your existing README.

Why it might be useful for your project:

• Your tool can be listed in the Open GAP Registry so other developers can discover and run it on any GAP-compatible runtime with zero extra config.
• The manifest captures your version, entrypoint (npx agent-flow-app), and supported runtimes (Claude Code + Codex) in a machine-readable way that other tooling can consume.
• Completely opt-in — feel free to tweak the files, request changes, or close if this is not something you want. Zero obligations either way.

Thanks for building Agent Flow in the open — it is a genuinely useful tool for the Claude Code ecosystem! 🙏

[cla-assistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

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