Discard stack dialog says it discards current events, but only future events are dropped #2701

The Discard confirmation dialog asks "Are you sure you want to discard all current stack events and discard any future events?" Discarding only changes the stack status. Existing events stay, and only new occurrences are dropped at ingestion.

Where

• Dialog text: mark-stack-discarded-dialog.svelte#L46-L57. It is used by the stack page, the status dropdown, and the bulk actions menu.
• Status change only updates the stack: StackHandler.cs#L216-L247
• New events for a discarded stack are dropped in the pipeline: 010_AssignToStackAction.cs#L129-L134

What happens

Users are told that existing events will be discarded. After confirming, all existing events for the stack remain searchable and still count toward history. The bulk wording also reads "N stacks events".

Expected

The dialog describes what happens: future occurrences are discarded and don't count against the plan limit, and existing events are kept. It could also point to deleting the stack for anyone who wants existing events removed.

Suggested fix

Reword the description, for example: "Future occurrences of this stack will be discarded and won't count against your event limit. Existing events are kept." Use "N stacks" for the plural.