feat: add MMKV cache persistence and image caching

Shiva Guptarequested to merge
feat/offline-persistence-and-image-cache into main

Stacked on !4

Summary

offline support + image caching for the Tablets feature

Changes

  • Query persistence - PersistQueryClientProvider + MMKV async persister (maxAge 24h). Feed restores on launch -> instant cold start, works offline
  • Image caching - cachePolicy="memory-disk" on card, list-row, and detail images -> instant re-display + survives restarts

Notes

  • Feed JSON -> MMKV; image files -> expo-image disk cache (two layers)
  • Offline images = only ones already viewed (no bulk prefetch)

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