[Feature]: Confirm before unpinning a thread

[f-trycua]

Before submitting

• I searched existing issues and did not find a duplicate.
• I am describing a concrete problem or use case, not just a vague idea.

Area

apps/web

Problem or use case

The Unpin thread action in Sidebar V2 takes effect immediately. It is easy to click by mistake while using the thread context menu, after which the thread leaves the pinned section and can be harder to find again.

Proposed solution

Show a confirmation dialog before unpinning a thread. The dialog should name the thread when possible, make Cancel the safe default, and require an explicit Unpin thread confirmation.

Mobile exposes the same immediate action, so matching behavior there would keep the clients consistent.

Why this matters

Pinned threads are usually kept there deliberately. A confirmation step would prevent accidental changes to that curated list and avoid making users search for and re-pin a thread.

Smallest useful scope

Add confirmation to the Sidebar V2 web/desktop context-menu action before dispatching thread.unpin.

Alternatives considered

An undo toast could also reduce the impact of accidental clicks. Confirmation is preferable here because it prevents the thread from moving out of the pinned section in the first place.

Risks or tradeoffs

This adds one click to an intentional unpin. The extra step seems reasonable because unpinning is relatively infrequent and immediately changes the thread's location.