fix: add ProGuard keep rules for UI screens and components

Navigation compose lambdas in NavGraph may not be traced by R8's call
graph, causing screen composables to be stripped in release builds.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/proguard-rules.pro

@@ -92,6 +92,13 @@
 # --- Keep WebSocketService (injected into ChatRepositoryImpl) ---
 -keep class top.yeij.cyrene.service.WebSocketService { *; }
 
+# --- UI screens & components (called via Navigation compose lambda — R8 may not trace) ---
+-keep class top.yeij.cyrene.ui.screens.** { *; }
+-keep class top.yeij.cyrene.ui.components.** { *; }
+-keep class top.yeij.cyrene.ui.overlay.** { *; }
+-keep class top.yeij.cyrene.ui.navigation.** { *; }
+-keep class top.yeij.cyrene.ui.theme.** { *; }
+
 # --- General AndroidX ---
 -keep class androidx.lifecycle.** { *; }
 -dontwarn androidx.lifecycle.**