Upgrade to React 19

[jwaspin]

Upgrade to React 19

Upgrade React and React DOM from v18.3.1 to v19.x for latest features, performance improvements, and long-term support.

Current Status

• React 19 released December 2024 (14 months mature)
• All dependencies ready for React 19
• defaultProps deprecation already fixed in previous PR

Why

• React 18 approaching end-of-support phase
• React 19 is production-ready and widely adopted
• Better performance and optimizations
• Future-proof the application
• Unlock new React features

Prerequisites

• React Redux v9 upgrade completed
• Material-UI v6 upgrade completed
• All tests passing on current versions

Tasks

• Update react to ^19.0.0
• Update react-dom to ^19.0.0
• Update @types/react to ^19.0.0
• Update @types/react-dom to ^19.0.0
• Run pnpm install
• Review React 19 migration guide
• Check for ref-related changes
• Run full test suite: pnpm test
• Run linter: pnpm lint
• Test encryption/IndexedDB features thoroughly
• Test all views and user workflows
• Verify no hydration warnings (StrictMode)
• Update CHANGELOG.md with React version

Acceptance Criteria

• All 221 tests pass
• No linting errors
• No React warnings in console
• All features work correctly:
  • Account creation/management
  • Transaction CRUD operations
  • Statement generation
  • Recurring transactions
  • Category management
  • Data encryption/decryption
  • Import/Export functionality
• No performance regressions

Notes

• defaultProps already migrated to ES6 defaults (✅ done)
• No class components in codebase (✅ hooks only)
• Expected to be smooth upgrade
• Estimated effort: 1-2 hours including thorough testing