Replace deprecated Zod .merge(z.object({...})) with .extend({...}) for AthenaOverrideConfigSchema. Add council-member to AgentOverridesSchema to match OverridableAgentNameSchema.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>