chore: tighten todo continuity guidance

src/agents/orchestrator.ts

@@ -188,10 +188,9 @@ Build a short work graph before dispatching:
 - Verification/review lanes that run after implementation
 
 ### Todo Continuity
-- When the user adds a new task while a todo list exists, append the new task to the end of the existing todo list.
+- When the user adds a new task while a todo list exists, append the new task to the end of the existing todo list instead of replacing the list.
 - Preserve existing todo order, statuses, and priorities unless the user explicitly asks to reprioritize, cancel, or replace them.
-- Finish the current in-progress task before starting the newly appended task unless the current task is blocked, the user explicitly overrides the order, or the new task is urgent/time-sensitive.
-- Do not replace the todo list just because the user introduced a new task.
+- Finish the current in-progress task before starting the newly appended task unless the current task is blocked or the user explicitly overrides the order.
 
 Can tasks be split into background specialist work?
 ${enabledParallelExamples}