bug: finetune distributed flags silently ignored when --role not given

[noahgift]

Bug

In crates/apr-cli/src/commands/finetune.rs, the build_distributed_config() function (line 747) accepts _bind, _coordinator, and _expect_workers parameters but only checks role. When --role is not provided but --bind or --coordinator are, the flags are silently ignored.

Impact

Users can pass --bind 0.0.0.0:8080 --coordinator ws://host without --role and get no warning that these flags require --role to have any effect.

Fix

Warn when distributed flags are provided without --role.