[Feature]: Allow manually reordering threads in Sidebar V2

[Newarr]

Area

apps/web

Problem or use case

I want to drag threads into the order I plan to work through them. Sidebar V2 currently controls the order for me.

Proposed solution

Add a Manual thread sort mode, like the existing manual project sort. Let me drag threads within a project and keep that order after reload.

Why this matters

Thread order often represents priority or dependency, which automatic sorting cannot know.

Smallest useful scope

Manual ordering for active, unpinned threads within one project. Pinned, Snoozed, and Settled threads can keep their current behavior.

Alternatives considered

Pinning only helps a few threads. #6342 and #4695 propose automatic ordering, not user-defined order.

Risks or tradeoffs

New threads need a predictable place in the manual order.

Examples or references

The project list already supports manual drag ordering.

Contribution

• I would be open to helping implement this.

[Torrey-Smith-165]

Desperately in need of this feature. Similar open issue at Issue #6432 for reference. Again, I'm happy to put up a PR for this feature if given blessing.