feat: add Hermes Agent to the ACP Registry

[1xxalexx1]

Summary

Add Hermes Agent as an ACP Registry agent for Zed and other ACP-compatible clients.

Hermes already implements the ACP server contract, including:

• provider-aware model enumeration in session/new
• model switching through session/set_model
• terminal and agent authentication methods
• editor-facing tool calls, diffs, terminal activity, approvals, and session modes

The companion launcher package is being prepared in NousResearch/hermes-agent#88578. It exposes the executable shape required by the registry and starts the user's installed hermes-acp runtime rather than creating a second Hermes installation.

Validation

With URL validation skipped (the manifest schema, icon, and registry build all pass):

SKIP_URL_VALIDATION=1 python .github/workflows/build_registry.py --dry-run
Dry run: validated 40 agents successfully

The normal build is intentionally blocked until @nousresearch/hermes-agent@0.20.2 is published to npm:

npm package not found: @nousresearch/hermes-agent

This PR is draft until the launcher package is published. Once published, rerun the registry build and the auth check, then mark this ready for review.

[1xxalexx1]

Updated the draft manifest to Hermes 0.20.3, matching current upstream main. Local npm-pack smoke test now passes through the launcher: ACP initialize reports Hermes 0.20.3, terminal auth, 350 available models, and 3 session modes. The only remaining CI blocker is publication of @nousresearch/hermes-agent@0.20.3.

[1xxalexx1]

Found and fixed the actual Zed UI gap in NousResearch/hermes-agent#88630: Hermes was returning ACP models, but Zed 1.15 renders external-agent selectors from session/new.configOptions and sends session/set_config_option. The fix exposes the provider-aware model catalog as a model select option and routes selection through Hermes model switching. Local live smoke: 350 options, selection round-trip passed.