Fix onboarding UX and add replaceable journey analytics

Make recipient changes explicit, prioritize verification retry, and label simulated outcomes prominently. Add shared typed analytics with bounded dummy capture, correlated service events and documented PostHog adapter contract. Validate privacy, retries, abandonment, keyboard recovery and accessibility. Related to #12.

frontend/packages/sxchnge_auth/README.md

@@ -61,3 +61,8 @@ When a supported sxchnge BFF contract exists, implement transport DTOs and mappe
 `VerificationService` exposes `send(email, locale)` and `confirm(token)` as named-argument methods. Inject an implementation into `VerificationProvider`, shared by web and mobile. The provider exposes immutable `VerificationState` (idle/sending/sent/checking/verified/expired/invalid/error), suppresses concurrent duplicate operations, and ignores completions after reset or disposal. Typed `VerificationException` maps confirmation failures; unknown exceptions become internal errors without exposing exception text. Sending failures always become the general error state.
 
 `DummyVerificationService` supports `demo-valid`, `demo-expired`, and `demo-internal` confirmation tokens; other tokens are invalid. Configure `delay` and `sendFailure` for tests. Results are explicitly simulated. It performs no network, storage, mail delivery, or account mutation. A production adapter must implement backend validation, delivery, rate limits, and safe token handling; this client provider is not an authorization boundary.
+
+`InstrumentedAuthServices` decorates the three auth service interfaces with a
+shared `JourneyRecorder` from `sxchnge_analytics`. It preserves results/exceptions
+for providers while emitting only typed semantic outcomes. `SimulationInfo`
+allows decorators and UI to identify preview services before the first result.