Add endoscopy result viewer screen

New screen for viewing endoscopy results: 2×2 snapshot grid with
simulated endoscopic view (radial gradient + specular highlight),
diagnosis chips, conclusion, numbered recommendations, PDF/share
actions, and full-screen image viewer with pagination.

Wired via nav route `result:<id>` from ResultsScreen and exposed in
Tweaks screen selector.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/App.jsx

@@ -60,6 +60,7 @@ const SCREEN_OPTIONS = [
   { id: 'appt:a1', lb: 'Детали приёма' },
   { id: 'results', lb: 'Результаты' },
   { id: 'result-audio', lb: 'Аудиограмма' },
+  { id: 'result:r2', lb: 'Эндоскопия носоглотки' },
   { id: 'recovery', lb: 'Восстановление' },
   { id: 'audiotest', lb: 'Тест слуха' },
   { id: 'chat',    lb: 'Чат' },