Feature Request: Require all assignees to complete/approve before a task moves forward

Use case: We run creative briefs with chained subtask dependencies (Copy Dev → Layout & Design → ICR Review → Copy Edits → Design Edits → Proof → Release). At the review/approval stages, multiple people need to sign off before work should advance to the next step.

Current limitation: When a task has multiple assignees, any single person can mark it complete, which unblocks the dependency chain. There's no way to require that all assignees approve or complete the task before it's allowed to close or trigger the next dependent task.

Requested behavior: A task-level setting (or a new approval task type) where completion requires sign-off from every assignee. The task stays open and dependencies stay blocked until all assigned approvers have individually marked it done/approved.

Why it matters: Without this, teams either have to split one review step into multiple parallel sub-subtasks (adding clutter), or manually police that everyone has actually reviewed before moving forward. A native "require all" option would keep workflows clean and prevent work from advancing prematurely.