Initial public release.

• FirebaseProvider forwards every UniTrack event to Firebase Analytics with name + parameter sanitisation that matches Firebase's strict rules.
• Super properties + user properties (init-time + runtime mutations).
• Helpers shipped alongside the provider:
  • UniTrackFirebaseMessaging — handles FCM token updates + push notifications (foreground, click, background). Plumbs into UniTrack.trackNotification and emits fcm_token_updated.
  • UniTrackFirebaseCrashlytics — recordError, setCustomKey, log, syncUser. Records to Crashlytics AND fires application_error so the portal sees the same incident.
  • UniTrackFirebaseRemoteConfig — Firebase RC activation + getString/Bool/Int/Double getters. Plugs into the unified UniTrack.getRemoteValue<T> resolver chain.
• Optional portal mirror so the UniTrack portal can show a copy of every event tagged provider=firebase.