test: cover TransactionPanel and wallet E2E flows

[0takuc0mrade]

Summary

• add provider-backed TransactionPanel tests for validation, payload submission, success/error rendering, reset behavior, and Enter-key submission
• fix Enter-key submission for inputs while preserving the existing validation and preview flow
• add Playwright configuration and a wallet-flow smoke test covering connect, Transactions navigation, paginated history, and payment success hash
• render the existing paginated TransactionHistory on the Transactions screen
• run the Chromium E2E suite in CI for pull requests targeting main
• repair the malformed root CSS token block and align Tailwind with the existing v4 Vite integration so the Vite dev server can support E2E tests

Verification

• npm test -- --run src/components/TransactionPanel.flow.test.tsx (8 passed)
• npm run test:e2e (1 passed, Chromium)
• npm run build:app
• changed TypeScript/TSX files pass ESLint

The repository-wide test/lint/typecheck commands still report unrelated failures already present on main, including stale client mocks, two unused declarations, and Vite/Vitest type-version conflicts.

Closes #598
Closes #605

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