Fix Hermes plugin v0.14 compatibility

[humandebri]

Summary

• add a root Hermes plugin entrypoint so the v0.14 directory plugin loader can call register(ctx)
• include that entrypoint in the CLI-managed Hermes plugin payload
• accept Hermes v0.14 transform_llm_output response_text hook arguments

Validation

• python -m unittest plugins.hermes.tests.test_plugin
• cargo test -p kinic-vfs-cli --lib hermes