Remove the drag-right-to-go-back gesture

The screen no longer follows a horizontal drag. Back is the arrow at the
top left and the platform's own edge gesture, both unchanged.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/androidApp/src/main/kotlin/com/example/aiapp/AppRoot.kt

@@ -198,21 +198,17 @@ fun AppRoot(
             // row key. Only reachable since a notification can move straight from one session to
             // another; every other way here passes through [Screen.Main], which disposes it anyway.
             key(here.summary.id) {
-                // The gesture goes on a box around the screen rather than inside it, so it is the
-                // outermost thing in the tree and everything within has already had its chance at
-                // the drag. See [swipeBack]. No imePadding here, for the reason above.
-                Box(Modifier.swipeBack(goToMain)) {
-                    SessionScreen(
-                        settings = current,
-                        summary = here.summary,
-                        onBack = goToMain,
-                        share = share,
-                        onShareTaken = { share = null },
-                    )
-                }
+                // No imePadding here, for the reason above.
+                SessionScreen(
+                    settings = current,
+                    summary = here.summary,
+                    onBack = goToMain,
+                    share = share,
+                    onShareTaken = { share = null },
+                )
             }
         is Screen.Spawn ->
-            Box(Modifier.imePadding().swipeBack(goToMain)) {
+            Box(Modifier.imePadding()) {
                 SpawnScreen(
                     settings = current,
                     onSpawned = { spawned ->
@@ -223,7 +219,7 @@ fun AppRoot(
                 )
             }
         is Screen.Settings ->
-            Box(Modifier.imePadding().swipeBack(goToMain)) {
+            Box(Modifier.imePadding()) {
                 SettingsScreen(
                     existing = current,
                     onSaved = { saved ->