Add split pane UI for new conversation screen.

app/src/main/java/org/thoughtcrime/securesms/components/ContactFilterView.java

@@ -25,8 +25,13 @@ import org.thoughtcrime.securesms.util.ServiceUtil;
 import org.thoughtcrime.securesms.util.TextSecurePreferences;
 import org.thoughtcrime.securesms.util.ViewUtil;
 
+/**
+ * A search input field for finding recipients.
+ * <p>
+ * In compose, use RecipientSearchField instead.
+ */
 public final class ContactFilterView extends FrameLayout {
-  private   OnFilterChangedListener listener;
+  private OnFilterChangedListener listener;
 
   private final EditText        searchText;
   private final AnimatingToggle toggle;

app/src/main/java/org/thoughtcrime/securesms/components/compose/ScreenTitlePane.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2025 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.components.compose
+
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.dp
+import org.thoughtcrime.securesms.window.WindowSizeClass
+
+/**
+ * Displays the screen title for split-pane UIs on tablets and foldable devices.
+ */
+@Composable
+fun ScreenTitlePane(
+  title: String,
+  modifier: Modifier = Modifier
+) {
+  val windowSizeClass = WindowSizeClass.rememberWindowSizeClass()
+
+  Text(
+    text = title,
+    style = MaterialTheme.typography.headlineLarge,
+    color = MaterialTheme.colorScheme.onSurface,
+    modifier = modifier
+      .padding(
+        start = if (windowSizeClass.isExtended()) 80.dp else 20.dp,
+        end = 20.dp,
+        top = 12.dp,
+        bottom = 12.dp
+      )
+  )
+}