find
Look up a DomainType by exact DomainType.name (FQN or whatever the type was registered under) and fall back to a simple-name match (name.substringAfterLast('.')). Lets callers refer to a type by its natural simple name in YAML / spec form even though the platform registered the JVM-backed type under its FQN. Returns null so callers can chain other lookups (classpath, etc.) before throwing.
Shared by AgentScope.resolveType and downstream action / goal machinery so the lookup behaves identically everywhere.