refactor(agent-key): use getAgentListDisplayName for consistent key remapping

Update agent key remapper and tests to use getAgentListDisplayName

for proper runtime-facing list names in OpenCode display.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>