Production deployment setup + feature complete

- Dockerfile + deploy.sh for Hetzner server
- Email verification via Better Auth + Resend
- Invite code flow (6-digit OTP, generate/join)
- Settlement share percent fix (payer vs debtor)
- OCR scanner fixes (date display, retry, viewfinder)
- app.json icon/splash/adaptive-icon configured
- iOS deployment target 15.5 (ML Kit requirement)
- DB migration 0014: household_invitations table

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -49,3 +49,10 @@ coverage
 .cache
 tmp
 temp
+
+# Expo prebuild (generated native code)
+apps/native/ios/
+apps/native/android/
+
+# Production env
+apps/native/.env.production