Room upgrades delist room pins — Concern for v12 upgrade

### Your use case

I would like to raise a concern regarding the current behavior of room upgrades as it relates to room pins (pinned messages). When a room is upgraded, the pins from the predecessor room are not migrated to the successor room, which results in the loss or delisting of important pinned messages for all members.

**Issue Description**

When a room is upgraded, the newly created room does not retain the pins set in the previous room. This causes a loss of context or critical information that was surfaced via pins, which negatively affects user experience especially in larger or information-centric communities.

**Why this is important**

Pins are often used as quick-reference material for rules, resources, or ongoing discussions. Losing this content in the course of a room upgrade is disruptive and can be confusing for members who rely on them for community guidelines or important links.

**Suggested Approach for v12 (Room Version 12) and Room Upgrades**

Please consider implementing a mechanism for migrating pinned messages from the predecessor to the successor room during room upgrades. At minimum, warning admins/users before upgrade about potential loss of pins and perhaps providing export/import options.
Alternatively, document a recommended manual process or provide tooling to help communities preserve their pins through upgrades.

**Questions**

Is there anything planned for v12 around this behavior?
Are there technical reasons pins cannot be migrated, or is this a missing feature?
Do you have recommendations for community admins to mitigate this issue during upgrades?

### Have you considered any alternatives?

Not to do room upgrade

### Additional context

_No response_

The issue names no files, tests, or entry points; first inspect the room-upgrade and pinned-message behavior and clarify whether migration, warnings, export/import, or documentation is in scope. Done should be defined as preserving pins across v12 upgrades or documenting a tested mitigation.

Written by the indexing model from the issue text.