fix: remove AnimatedVisibility from chat bubbles to fix LazyColumn scroll limit

AnimatedVisibility with visible=false starts items at zero height. Inside a
reverseLayout LazyColumn, this causes the list to miscompute total content
height, preventing items beyond the visible viewport from being composed.
This was limiting the chat to ~9 visible messages that filled the screen.

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

app/src/main/java/top/yeij/cyrene/ui/screens/chat/ChatScreen.kt

@@ -1,8 +1,5 @@
 package top.yeij.cyrene.ui.screens.chat
 
-import androidx.compose.animation.AnimatedVisibility
-import androidx.compose.animation.fadeIn
-import androidx.compose.animation.slideInVertically
 import androidx.compose.foundation.background
 import androidx.compose.foundation.gestures.detectDragGesturesAfterLongPress
 import androidx.compose.foundation.layout.Box
@@ -67,25 +64,12 @@ import top.yeij.cyrene.ui.components.TypingIndicator
 import top.yeij.cyrene.util.RecordState
 import top.yeij.cyrene.viewmodel.ChatViewModel
 import top.yeij.cyrene.viewmodel.SettingsViewModel
-import kotlin.math.min
+
 
 @Composable
 private fun AnimatedChatBubble(
     message: Message,
     animIndex: Int,
-) {
-    var visible by remember { mutableStateOf(false) }
-    LaunchedEffect(Unit) {
-        delay(min(animIndex, 10) * 60L)
-        visible = true
-    }
-    AnimatedVisibility(
-        visible = visible,
-        enter = fadeIn(animationSpec = androidx.compose.animation.core.tween(300)) +
-            slideInVertically(
-                animationSpec = androidx.compose.animation.core.tween(300),
-                initialOffsetY = { it / 4 },
-            ),
 ) {
     ChatBubble(
         content = message.content,
@@ -94,7 +78,6 @@ private fun AnimatedChatBubble(
         timestamp = message.timestamp,
     )
 }
-}
 
 @Composable
 fun ChatScreen(