feat: SDK identity, last-click attribution, and screen-view tracking

[onamfc]

Summary

Brings the Android SDK up to the React Native / Expo feature line, across three additive capabilities:

• SDK identity — sdkName/sdkVersion on the install and event payloads plus an X-LinkForty-SDK header on all requests (sourced from BuildConfig, so it always matches the published artifact). Lets the backend report which SDKs and versions are in use.
• Last-click attribution — every in-app event is stamped with the deep link that most recently opened the app (deferred install or direct re-engagement) plus a per-app-open sessionId. The newest open supersedes the previous one, the active link persists across app restarts, and activity with no preceding deep-link open stays organic (session only). The conversion window is applied server-side at query time.
• Screen-view tracking — LinkForty.shared.trackScreenView(name) plus a LinkFortyNavObserver for automatic tracking: it's a Jetpack Navigation OnDestinationChangedListener that reports each destination's route/label. androidx.navigation is a compileOnly dependency, so apps that don't use Jetpack Navigation are unaffected. Both emit screen_view events (with screen/previousScreen) carrying the attribution stamp.

All changes are additive and backward compatible; no integration changes are required for existing apps.

Implementation notes

• New AttributionContext holds the active { linkId, clickId?, openedAt } + rotating sessionId, persisted via StorageManager; updated at both deep-link delivery seams in DeepLinkHandler and stamped onto each event by EventTracker.
• EventRequest gains nullable attributedLinkId/attributedClickId/linkOpenedAt/sessionId (Moshi omits nulls, so organic events stay clean).
• Wire format matches the other SDKs (screen_view event, screen/previousScreen in event data).

Testing

./gradlew :sdk:testDebugUnitTest — BUILD SUCCESSFUL, including new AttributionContext and event-stamping / screen-view coverage. Compiles against the compileOnly Jetpack Navigation dependency.

Docs

README and API reference are updated. A RELEASING.md documents the version bump (VERSION_NAME in gradle.properties, which flows to BuildConfig).