fix proguard rules for navigation component crash

R8 was obfuscating Navigator subclasses, breaking @Navigator.Name
annotation lookup at runtime and causing crash on app launch.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: zfdang

app/proguard-rules.pro

@@ -53,4 +53,11 @@
 -keep,allowobfuscation,allowshrinking class com.google.gson.reflect.TypeToken
 -keep,allowobfuscation,allowshrinking class * extends com.google.gson.reflect.TypeToken
 
-##---------------End: proguard configuration for Gson  ----------
+##---------------End: proguard configuration for Gson  ----------
+
+##---------------Begin: proguard configuration for Navigation  ----------
+# Keep Navigation component classes and their @Navigator.Name annotations
+# R8 obfuscates Navigator subclasses, breaking reflection-based lookup
+-keep class * extends androidx.navigation.Navigator { *; }
+-keep class androidx.navigation.fragment.NavHostFragment { *; }
+##---------------End: proguard configuration for Navigation  ----------