Project filter: select multiple projects (e.g. work vs personal sets) #22211

Today the project filter appears to support a single project (or all). I’d like to filter the thread list by multiple projects at once.

Why: I keep work and personal repos in the same T3 install. During work hours I want the sidebar to show only my work projects; off-hours only personal ones. Switching one project at a time doesn’t give that “mode” view.

Suggested behavior:

• Multi-select in the project filter (checkboxes or equivalent)
• Optional: named presets / saved sets (e.g. “Work”, “Personal”) that restore a multi-project selection in one click — nice-to-have, not required for v1

Out of scope guess: no change to how threads are bound to a single project; this is list filtering only.