#40796 refactor: React 19

Proposed changes (including videos or screenshots)

It upgrades the frontend to React 19.

Issue(s)

Steps to test or reproduce

Further comments

It might unexpectedly affect behavior in development mode due to changes on how Strict Mode works in React.

Task: ARCH-2195

Summary by CodeRabbit

• Bug Fixes

  • Improved error handling and fallback behavior for application error screens.
  • Refined event handling across messaging, filters, settings, contacts, and form inputs for better compatibility/stability.

• Tests

  • Expanded and stabilized automated messaging navigation and editing coverage, including attachment/emoji rendering and multi-context scenarios.
  • Added explicit toolbar-load waits to reduce UI timing flakiness.

• Chores

  • Upgraded React and related UI/tooling libraries to newer versions.