migrate pure-logic tests to vitest (phase 1)

vitest/sentry-stub.ts

@@ -0,0 +1,16 @@
+/*
+ * Stub for @sentry/react-native. The real package is CJS and requires
+ * `react-native` internally, which boots the native runtime under node. Many
+ * test-reachable modules pull it in transitively via #/logger. We only need
+ * the surface sentryTransport touches (src/logger/transports/sentry.ts).
+ *
+ * Aliased in place of @sentry/react-native via resolve.alias in
+ * vitest.config.ts. Tests that assert on Sentry calls (logger.test.ts) still
+ * vi.mock it directly, which takes precedence.
+ */
+import {vi} from 'vitest'
+
+export const addBreadcrumb = vi.fn()
+export const captureException = vi.fn()
+export const captureMessage = vi.fn()
+export const init = vi.fn()