feat: add prediction card touch ripple feedback

[pq198363-ops]

Summary

• Add touch-ripple press feedback for PredictionCard using a CSS pseudo-element on :active
• Respect prefers-reduced-motion and keep the existing 44px touch target/focus ring behavior
• Rebuild the focused PredictionCard test file, cover ripple CSS/classes, and remove the extensionless components/predictioncard file that shadows PredictionCard.tsx on Windows/Jest resolution
• Document the touch ripple utility in docs/touch-ripple.md

Closes #363

Verification

• node node_modules/jest/bin/jest.js components/__tests__/PredictionCard.test.tsx --runInBand passed: 12 tests
• node node_modules/eslint/bin/eslint.js components/PredictionCard.tsx components/__tests__/PredictionCard.test.tsx exited 0 with one pre-existing @next/next/no-img-element warning in PredictionCard.tsx
• git diff --check exited 0

Known baseline issues

• node node_modules/typescript/bin/tsc --noEmit still fails on unrelated existing files such as dashboard layout, wallet modal, disputes badges, navbar, and dialog code.
• Full Jest still fails on unrelated existing suites, including wallet modal getKit and events table accessibility expectations.

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