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

[computer-agent]

Hi! 👋 I came across the harness and wanted to propose GitAgent Protocol support — an open standard for portable, interoperable AI agents (https://gitagent.sh).

The harness is a great fit for GAP: it already embodies the protocol's core values (transparent prompts, markdown-defined agents, full runtime control). These two files simply make that explicit in a machine-readable, portable format.

What this adds (nothing else changes):

• agent.yaml — standard manifest: name, version, model, runtime entrypoint, 9 skills (TUI, web UI, A2A, memory, sandboxing, etc.), and LGPD compliance metadata
• SOUL.md — the harness's persona and operating principles in the standard soul format: transparency-first, zero hidden injection, faithful execution of IDENTITY.md

Why it might be useful:

• Makes the harness discoverable in the Open GAP registry
• Any GAP-compatible runtime or toolchain can introspect the manifest
• Documents the agent's capabilities and constraints in a portable, standard way
• Complements (not replaces) your existing IDENTITY.md / CLAUDE.md patterns

Totally optional to accept — feel free to tweak the agent.yaml fields to better match your intent, or close if it's not a fit. Thanks for building the harness in the open! 🦀