docs: Update comprehensive documentation with AI features, health checks, and architecture improvements

- Document automatic token verification on startup and note:// prefix for Markdown notes
- Add extensive AI capabilities section (Gemini integration, auto-tagging, content classification, multi-model fallback)
- Document link health monitoring system with dead link detection and exclusion features
- Add file sharing support (Markdown/text files) and deep links documentation
- Update technology

app/proguard-rules.pro

@@ -104,9 +104,11 @@
 }
 -dontwarn kotlinx.coroutines.**
 
-# Keep ALL Application classes to prevent runtime crashes
--keep class com.shaarit.** { *; }
--keepclassmembers class com.shaarit.** { *; }
+# Keep only what is strictly needed for serialization and Room
+-keep class com.shaarit.data.dto.** { *; }
+-keep class com.shaarit.data.local.entity.** { *; }
+-keep class com.shaarit.domain.model.** { *; }
+-keep class com.shaarit.data.export.Exported* { *; }
 
 # Keep Hilt generated classes
 -keep class com.shaarit.Hilt_* { *; }