Coordinated Expo SDK 52 → 55 migration (replaces PRs #33 #39 #43)

[heznpc]

PRs #33 (expo group), #39 (react-test-renderer 18→19), #43 (test group incl. @testing-library/react-native 12→13 + jest-expo 52→55) can only be merged together — Expo SDK 55 requires React 19 + react-test-renderer 19 + @testing-library/react-native >=13.2 + jest-expo 55 in lockstep.

Closing those 3 PRs as individually unmergeable. Plan:

• Read Expo SDK 55 changelog for breaking changes
• Single migration PR bumping: expo 52→55, expo-router 4→5, expo-* peers, react 18→19, react-native 0.76→0.78, @testing-library/react-native 12→13, jest-expo 52→55, react-test-renderer 18→19
• Verify tests pass under React 19 (StrictMode/concurrent semantics)
• Verify EAS Build still works (RN 0.78 may need EAS profile updates)
• Bump CHANGELOG + README references

Track here, ship as one PR.