Add ability to use custom env variables for conductors

[moonray]

I would like to be able to run claude code using Z.ai's GLM models for conductors.
You already added the ability to add custom commands, which allows setting env variable for a command. I would like to be able to use env variables in the same way when running a conductor.

for reference again, this is how to get GLM models to work with claude code

ANTHROPIC_BASE_URL=https://api.z.ai/api/anthropic \
ANTHROPIC_AUTH_TOKEN=<token> \
ANTHROPIC_DEFAULT_HAIKU_MODEL=glm-4.7 ANTHROPIC_DEFAULT_SONNET_MODEL=glm-4.7 \
ANTHROPIC_DEFAULT_OPUS_MODEL=glm-5 \
claude