#4822 added a CompactionPolicy generic parameter and a policy argument
to AcpRuntime::new. #4822 and #4824 (which added acp_runtime's call)
were reviewed and CI'd independently and merged textually clean, so
neither build caught that the two conflict: forge/main fails to
compile with 'missing generics for struct AcpRuntime' and 'this
function takes 4 arguments but 3 were supplied'.
Parameterize AcpRuntime<hive_claude::NeverCompact>, matching this
crate's documented no-mid-turn-compaction design (session.rs's module
doc: subagents are bounded, single-batch work, not sessions long-lived
enough to need in-place compaction).
c01ddd8238