Colour what a shell printed, swipe back, and let a stopped session take a setting

Bash output arrived with its escape sequences in it, so a coloured diff or
test run was line noise around the thing being read. The sequences that
decide how text looks are spans now and every other one is dropped, with a
carriage return honoured the way a terminal honours it so a progress bar
shows its final state rather than every state it passed through.

A rightward drag anywhere on a session, spawn or settings screen steps back,
following the finger so it can be abandoned. It loses every argument: a
child that consumes horizontal drags -- a wide fence, a table, a selection
-- has already taken the gesture before this sees it.

Changing the model or the permission mode of a session with nothing running
was refused, in words about the driver, while the config had already taken
the value that its next start will use. Both now announce the stored setting
instead, through one function, since which of the pair it is does not change
the rule.

The model-switch warning no longer fires after a clear: the server reports
the context as unmeasured rather than zero afterwards, and the fallback
reading counted the whole conversation still on screen.

An image loading shows a spinner in the space it is about to fill, in the
transcript and in the composer's attachments alike.

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

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

@@ -198,16 +198,21 @@ 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) {
-                SessionScreen(
-                    settings = current,
-                    summary = here.summary,
-                    onBack = goToMain,
-                    share = share,
-                    onShareTaken = { share = null },
-                )
+                // 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 },
+                    )
+                }
             }
         is Screen.Spawn ->
-            Box(Modifier.imePadding()) {
+            Box(Modifier.imePadding().swipeBack(goToMain)) {
                 SpawnScreen(
                     settings = current,
                     onSpawned = { spawned ->
@@ -218,7 +223,7 @@ fun AppRoot(
                 )
             }
         is Screen.Settings ->
-            Box(Modifier.imePadding()) {
+            Box(Modifier.imePadding().swipeBack(goToMain)) {
                 SettingsScreen(
                     existing = current,
                     onSaved = { saved ->