Add the ability to pause a running task and resume a paused task directly
from the TaskPage. This includes showing contextual messages when a task
is paused (manual vs timeout) and proper error handling with dialogs for
API errors.
- Extract task action logic into reusable mutations (api/queries/tasks.ts)
- Move TaskActionButton to modules/tasks for better organization
- Add pause button to TaskStartingAgent component
- Show appropriate state messages for transitioning states (pausing,
canceling, deleting)