Add agentgateway and AGENTS.md under two new subcategories

[asish-singh]

Draft, opened to make the options in #29 concrete rather than to preempt the Domain Editors. If they would rather use different subcategory names, or place these two projects in existing subcategories, I will close this or rewrite it to match.

What

Adds two AAIF hosted projects that are currently absent from landscape/landscape.yml, each in a new subcategory.

agentgateway under a new Gateways & Control Planes subcategory in Agent Runtimes, Frameworks & Workflow Orchestration.

AGENTS.md under a new Conventions & File Formats subcategory in Protocols & Discovery Registries.

Why new subcategories

As set out in #29, neither fits cleanly today. Orchestration Runtimes covers frameworks that compose agent logic rather than infrastructure that routes traffic, and Prompt & Runtime Guardrails is about constraining model behaviour rather than routing, so a gateway and control plane belongs to neither. Communication Protocols holds MCP and A2A, which are wire protocols, whereas AGENTS.md is a repository file convention.

Both subcategories are also intended to generalise, since more gateway and proxy projects and more file format conventions are likely to arrive.

Metadata

Status is project: member for both, matching how the published aaif/aaif-landscape marks them and consistent with MCP here and with goose in #27. Homepage and repository URLs match that published landscape. Descriptions follow the objective, pre competitive wording required by docs/data-schemas.md, with no superlatives, and logo uses the existing placeholder.svg.

Validation

landscape/landscape.yml parses as YAML, and every item across all categories carries the required name, homepage_url, description and project fields, with project values within the allowed set and homepage URLs beginning with https://.

@thc1006 offered in #25 to prepare these entries once a subcategory is chosen, so I am happy to hand this over or to have them push to the branch if that is easier.

[asish-singh]

Checking in on this one and #31. Both have been open since late July, and I notice the landscape side generally has PRs waiting (#27 and #28 as well) while taxonomy definitions are moving. If the landscape lane is paused on purpose, or waiting on a decision like #29, happy to hold or rework these to fit. If a rebase or any change would help them along, tell me and I will do it.