[Resource Consumption] minimized iframes consume resources and are unbounded

Minimized iframe surfaces retain their live documents without a count limit so minimizing another browser never discards unsaved page state or turns reattachment into a reload.

Hidden iframes can still consume memory and run JavaScript, timers, sockets, and media. Retaining arbitrarily many minimized iframes therefore allows resource consumption to grow without a Dormouse-imposed bound.

Priority: low. This is an accepted tradeoff for preserving content state. A future improvement could warn users when retained iframe resource use is high. Do not silently evict or reload minimized documents to enforce a cap.

The current eight-surface parking cap is being removed as part of the minimize/reattach lifecycle fix. This issue tracks the resource-consumption follow-up, not reintroducing that cap.

Start by tracing the minimized iframe lifecycle and how retained documents consume resources. The issue does not name files, tests, thresholds, or a concrete implementation; clarify the warning behavior and its completion criteria before starting work.

Written by the indexing model from the issue text.