fix(onboarding): improve battery optimization screen layout and scrolling

Restructure BatteryOptimizationEnabledContent to use proper scrolling behavior and fixed button placement at the bottom. The changes ensure better usability by preventing content from being hidden behind buttons and allowing full content visibility through scrolling.

app/src/main/java/com/bitchat/android/onboarding/BatteryOptimizationScreen.kt

@@ -2,6 +2,8 @@ package com.bitchat.android.onboarding
 
 import androidx.compose.animation.core.*
 import androidx.compose.foundation.layout.*
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.*
 import androidx.compose.material.icons.outlined.*
@@ -75,7 +77,16 @@ private fun BatteryOptimizationEnabledContent(
     colorScheme: ColorScheme,
     isLoading: Boolean
 ) {
+    // -------------- Fix Start for this method(BatteryOptimizationEnabledContent)-----------
     Column(
+        modifier = Modifier.fillMaxSize()
+    ) {
+        // Scrollable content area
+        Column(
+            modifier = Modifier
+                .weight(1f)
+                .verticalScroll(rememberScrollState())
+                .padding(bottom = 16.dp),
             verticalArrangement = Arrangement.spacedBy(24.dp),
             horizontalAlignment = Alignment.CenterHorizontally
         ) {
@@ -141,8 +152,20 @@ private fun BatteryOptimizationEnabledContent(
                 }
             }
             
-        Spacer(modifier = Modifier.height(8.dp))
+            Text(
+                text = stringResource(R.string.battery_optimization_note),
+                style = MaterialTheme.typography.bodySmall.copy(
+                    color = colorScheme.onSurfaceVariant
+                ),
+                textAlign = TextAlign.Center
+            )
+        }
         
+        // Fixed buttons at the bottom
+        Column(
+            verticalArrangement = Arrangement.spacedBy(12.dp),
+            horizontalAlignment = Alignment.CenterHorizontally
+        ) {
             Button(
                 onClick = onDisableBatteryOptimization,
                 modifier = Modifier.fillMaxWidth(),
@@ -179,16 +202,10 @@ private fun BatteryOptimizationEnabledContent(
                     Text(stringResource(R.string.battery_optimization_skip))
                 }
             }
-        
-        Text(
-            text = stringResource(R.string.battery_optimization_note),
-            style = MaterialTheme.typography.bodySmall.copy(
-                color = colorScheme.onSurfaceVariant
-            ),
-            textAlign = TextAlign.Center
-        )
         }
     }
+    // -------------- Fix Ended for this method(BatteryOptimizationEnabledContent)-----------
+}
 
 @Composable
 private fun BatteryOptimizationCheckingContent(