Configure multi_agent_v2 spawn agent hints

[pakrym-oai]

Allow multi_agent_v2 features to have its own temporary configuration under [features.multi_agent_v2]

[features.multi_agent_v2]
enabled = true
usage_hint_enabled = false
usage_hint_text = "Custom delegation guidance."
hide_spawn_agent_metadata = true

Absent usage_hint_text means use the default hint.

[features]
multi_agent_v2 = true

still works as the boolean shorthand.

[andmis]

Can we have the ability to configure the usage hint text?

[pakrym-oai]

Can we have the ability to configure the usage hint text?

Done