Radix to Base UI Migration (shadcn)

Execute migration in four passes. Keep each pass small and compilable.

1) Remove Radix package surface and switch imports

1. Remove Radix primitive packages from dependencies.
2. Add Base UI package(s) used by the project.
3. Replace Radix imports with Base UI imports component-by-component.
4. Keep component names stable during this pass (use aliases if needed) to reduce diff size.

Use references/checklist.md for pass order and validation gates.

2) Replace asChild composition with Base UI render composition

1. Find trigger/content compositions that relied on asChild.
2. Replace asChild usage with Base UI render-based composition.
3. Preserve semantic HTML and avoid nested interactive elements.
4. Re-test keyboard and focus behavior for each migrated trigger.