List Published A2A Agents

Every agent of the caller's that is currently reachable over A2A.

Exists so "which of my agents are exposed to the outside world" is answerable in one place. Per-agent toggles alone make that question require opening each agent in turn, which is exactly how someone loses track of what they have published.

Scoped to agents this caller actively OWNS, not merely controls in some other capacity - so it can never be used to enumerate other people's published agents, and a non-owner controller (e.g. delegated admin access) never sees an agent listed as theirs to publish.