Migrate buttons from AppCompat/MaterialComponents to Material3 styles

- troubleshooting.xml: Widget.AppCompat.Button.Borderless.Colored → Widget.Material3.Button.TextButton
- activity_onboarding.xml: Widget.AppCompat.Button.Borderless → Widget.Material3.Button.TextButton
- list_item_trackers_header.xml: Theme/Widget.MaterialComponents → Theme/Widget.Material3

https://claude.ai/code/session_01YWBt21ZE6WvhgivEEF6ED2

Author: claude

app/src/main/res/layout/activity_onboarding.xml

@@ -25,7 +25,7 @@
 
     <Button
         android:id="@+id/btnPrevious"
-        style="@style/Widget.AppCompat.Button.Borderless"
+        style="@style/Widget.Material3.Button.TextButton"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginStart="16dp"

app/src/main/res/layout/list_item_trackers_header.xml

@@ -155,8 +155,8 @@
 
             <com.google.android.material.button.MaterialButton
                 android:id="@+id/btnAnalyzeTrackers"
-                android:theme="@style/Theme.MaterialComponents.DayNight"
-                style="@style/Widget.MaterialComponents.Button.OutlinedButton"
+                android:theme="@style/Theme.Material3.DayNight"
+                style="@style/Widget.Material3.Button.OutlinedButton"
                 android:layout_width="0dp"
                 android:layout_height="wrap_content"
                 android:layout_marginTop="12dp"

app/src/main/res/layout/troubleshooting.xml

@@ -53,7 +53,7 @@
 
             <Button
                 android:id="@+id/btnBattery"
-                style="@style/Widget.AppCompat.Button.Borderless.Colored"
+                style="@style/Widget.Material3.Button.TextButton"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="@string/troubleshooting_battery_action"
@@ -87,7 +87,7 @@
 
             <Button
                 android:id="@+id/btnDataSaver"
-                style="@style/Widget.AppCompat.Button.Borderless.Colored"
+                style="@style/Widget.Material3.Button.TextButton"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="@string/troubleshooting_datasaver_action"
@@ -153,7 +153,7 @@
 
             <Button
                 android:id="@+id/btnVpnSettings"
-                style="@style/Widget.AppCompat.Button.Borderless.Colored"
+                style="@style/Widget.Material3.Button.TextButton"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="@string/troubleshooting_alwayson_action" />