fix(frontend): restore the imports the #751 merges dropped

[alex-dembele]

Refs #751. This does not close it: #751 is the premium UI epic, and this only repairs merge damage on master.

Problem

npm run type-check fails on master:

src/features/organization/MembersView.tsx(487,30): error TS2304: Cannot find name 'DeleteButton'.
src/features/risks/CreateRiskModal.tsx(241,16): error TS2304: Cannot find name 'ScrollProgress'.

Both components are exported by shared/ds. The imports were lost in the #751 phase merges. The same merge left an unused useMemo import in CreateRiskModal.tsx, which eslint rejects (@typescript-eslint/no-unused-vars).

It blocks criterion 4 of #807 (PR #832), which requires a green type-check.

Change

Three import lines, no logic change.

Verification

$ npm run type-check            → exit 0 (was 2 errors on master)
$ npx eslint MembersView.tsx CreateRiskModal.tsx   → 0 errors, 1 warning (the pre-existing react-hook-form watch() compiler notice)
$ npx prettier --check …        → clean
$ npx vitest run src/features/organization src/features/risks
  Test Files  6 passed (6) · Tests  40 passed (40)

Honest remainders

No browser pass. This PR restores imports that the rendered code already referenced, so on master these screens currently throw a ReferenceError when the delete button or the progress bar renders. After this PR they render again.