fix(design-system): improve trust badge and feedback accessibility

[snkk2x-collab]

Summary

• make tooltip-enabled trust badges keyboard reachable and give them an accessible label that includes the state explanation
• preserve non-tooltip badges as non-focusable presentational status pills
• respect OS/browser reduced-motion preferences in feedback notification entrance and exit transitions
• add regression coverage for the trust badge keyboard/name behavior

Fixes #967

Before / After

Before, a tooltip-enabled trust badge rendered as a non-focusable span, so keyboard users could not reach the explanation. Feedback notifications also always used spring motion. After this change, tooltip badges expose a keyboard focus target and accessible state explanation, while feedback toasts use near-static opacity transitions when reduced motion is requested.

Validation

• pnpm exec vitest run src/features/design-system/components/trust-badge.test.tsx
• pnpm exec tsc --noEmit
• pnpm exec eslint src/features/design-system/components/trust-badge.tsx src/features/design-system/components/trust-badge.test.tsx src/features/design-system/feedback/feedback-viewport.tsx