Create a new roadmap for remainder of 2026

**Is your feature request related to a problem or challenge? Please describe what you are trying to do.**
There has been an increase in contributions from multiple contributors and companies recently. I think it would be a good idea to discuss a roadmap for the remainder of 2026 (~4 months) so that we communicate to the community what we are working on and where we are looking for help (contributing, reviewing, testing, etc).

**Describe the solution you'd like**
Let's use this issue to discuss what everyone plans on workong on over the next few months, then we can create (or update) a roadmap section in the contributor guide.

**Describe alternatives you've considered**

**Additional context**

Start by reading the discussion in issue #2299 about plans for the remainder of 2026 and the existing contributor guide. Identify the agreed priorities, areas needing contribution, review, or testing, and the roadmap section to create or update. Done means the guide communicates the agreed roadmap and ways the community can help.

Written by the indexing model from the issue text.