Polish decision evidence on phones and in tone

- Below 640px evidence opens as a bottom sheet and lifts the card's
  actions above it; wider viewports fall back below or above the card
  before ever covering it.
- The dialog takes focus itself, so the close control opens without a
  tooltip; the close drops its title.
- Opposed-by rings use the warning tone, matching objections.
- The summary trigger gains a chevron and pointer cursor.
- Motion comes from the host's popover contract, with a sheet variant.
- A leading "I object:" marker is dropped from objection quotes.
- Fix the evidence-hover native fixture's missing useState import.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>