add tests for chat log event cache handling

Covers the recently fixed bugs (batch continuation on unknown convos,
accept status propagation to 'all'-status caches, rev guard against
stale writes) plus core per-log-type cache behaviors. Fixture builders
are shared for other chat test suites.

Stubs the bottom-sheet native module in jest setup: it reads
Platform.Version at import time, which jest-expo leaves undefined,
crashing any test that imports the chat/session chain.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

jest/jestSetup.js

@@ -23,6 +23,7 @@ jest.mock('react-native-safe-area-context', () => {
     SafeAreaProvider: jest.fn().mockImplementation(({children}) => children),
     SafeAreaConsumer: jest
       .fn()
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-call
       .mockImplementation(({children}) => children(inset)),
     useSafeAreaInsets: jest.fn().mockImplementation(() => inset),
   }
@@ -106,3 +107,19 @@ jest.mock('expo-modules-core', () => ({
 jest.mock('expo-localization', () => ({
   getLocales: () => [],
 }))
+
+// The bottom-sheet native component reads Platform.Version at import time,
+// which the jest-expo preset leaves undefined, crashing any test that pulls in
+// the chat/session import chain. Stub the native module so it's never
+// evaluated under jest.
+jest.mock('../modules/bottom-sheet', () => ({
+  __esModule: true,
+  BottomSheet: () => null,
+  BottomSheetNativeComponent: class {},
+  BottomSheetOutlet: () => null,
+  BottomSheetPortalProvider: jest
+    .fn()
+    .mockImplementation(({children}) => children),
+  BottomSheetProvider: jest.fn().mockImplementation(({children}) => children),
+  BottomSheetSnapPoint: {Hidden: 0, Partial: 1, Full: 2},
+}))