Two fixes:
1. Revert tool_execution_* forwarding: these cluttered the UI with raw
bash/read output the user never asked for. Only text_delta, system_event
and ui_request are forwarded, as before.
2. tht ignores THT_CONFIG env var and always looks for config/tht.yaml
relative to CWD. Create a symlink so the PI agent can run tht commands
without -c flag.