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

[shreyas-lyzr]

Hi Simon! 👋

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

Agent Flow already does something beautiful: it makes Claude Code and Codex orchestration visible. GAP lets it also be portable — listed in the open registry, runnable on any GAP-compatible runtime, and discoverable by the growing community building on the standard.

What this adds (nothing else changes):

• agent.yaml — a standard manifest describing Agent Flow's purpose, version (0.8.1), license (Apache-2.0), runtime, and skills
• SOUL.md — your agent's persona and behavior distilled into the standard soul format

With these two files, Agent Flow can be listed on https://registry.gitagent.sh and run on any GAP-compatible harness alongside other Claude Code agents. Totally optional to accept — feel free to tweak the descriptions or close if it's not a fit. Thanks for building Agent Flow in the open! 🙌

[cla-assistant]

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