Threads a nextPhase parameter (wait/merge/wait_final/merge_final, validated
by the new MergeHelperPhase) from handoff_list_handler through
HubBroadcaster/WorkerHub into InteractiveLaunchSpecService, which now picks
the next session's system prompt (MergeHelperWait/MergeHelperMerge) and
model (HandlerWaitAlias/HandlerMergeAlias) from it instead of hardcoding the
old two-phase Execute prompt -- this also fixes a build break left by the
prior prompt-split task, which removed PromptKind.MergeHelperExecute without
updating its only caller.
Also sets --model/--effort/--permission-mode explicitly for every list-handler
session (Triage included) via PermissionModeResolver instead of inheriting the
CLI's ambient model and hardcoding "auto", and adds Task to the merge-helper
allowlist so the Merge phase can delegate diff reviews to subagents.
mika kuns
f2609d186a