Revert "Open a row downwards, from whichever end was pressed"

This reverts commit f4d4c82. The anchoring it added made the transcript
jump on every expand and collapse, and left the list snapping back to the
bottom when somebody scrolled up, which is worse than the upward-opening
it was meant to fix.

Two things to look at when this is retried. `LazyListItemInfo.offset` in a
`reverseLayout` list is not obviously the coordinate space this assumed,
so `offset + size` may have been measuring the bottom edge -- the one the
list already holds -- rather than the top. And the anchoring scroll ran in
a coroutine that could still be pending when the reader started dragging;
`scrollBy` takes the default mutation priority, so it cancels that drag.

Verify the next attempt with `uiautomator dump` -- node bounds in device
pixels, before and after a toggle -- rather than by eye from screenshots.

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

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

@@ -99,20 +99,6 @@ fun groupToolRuns(items: List<TranscriptItem>): List<TranscriptRow> {
     return rows
 }
 
-/**
- * Which end of a row a reader acted on, and therefore which end must not move.
- *
- * A row has two controls at opposite ends -- the heading that opens it and the bar that shuts it
- * again -- and the reader's finger is on one of them. Whichever it is has to stay where it is while
- * the row changes size, or the thing they just pressed slides out from under them. The list anchors
- * every row's bottom edge by default (see the transcript's `reverseLayout`), so [Bottom] is what
- * happens on its own and [Top] is what has to be arranged.
- */
-enum class RowEdge {
-    Top,
-    Bottom,
-}
-
 /**
  * Several calls under one heading, closed until somebody asks.
  *
@@ -127,15 +113,14 @@ enum class RowEdge {
 fun ToolGroup(
     group: TranscriptRow.Tools,
     expanded: Boolean,
-    /** Told which end was pressed, because this row has a control at each -- see [RowEdge]. */
-    onToggle: (RowEdge) -> Unit,
+    onToggle: () -> Unit,
     isToolExpanded: (String) -> Boolean,
     onToolToggle: (String) -> Unit,
     onAnswer: (questionId: String, answers: List<String>) -> Unit,
     image: @Composable (String) -> Unit,
 ) {
     if (!expanded) {
-        Card(Modifier.fillMaxWidth().clickable { onToggle(RowEdge.Top) }) {
+        Card(Modifier.fillMaxWidth().clickable(onClick = onToggle)) {
             Text(
                 "Called ${group.calls.size} tools",
                 style = MaterialTheme.typography.titleSmall,
@@ -148,7 +133,7 @@ fun ToolGroup(
         Text(
             "Called ${group.calls.size} tools",
             style = MaterialTheme.typography.titleSmall,
-            modifier = Modifier.fillMaxWidth().clickable { onToggle(RowEdge.Top) }.padding(12.dp),
+            modifier = Modifier.fillMaxWidth().clickable(onClick = onToggle).padding(12.dp),
         )
         group.calls.forEach { call ->
             ToolCard(
@@ -159,9 +144,7 @@ fun ToolGroup(
                 image = image,
             )
         }
-        // Shutting it from here anchors the other end: the reader is at the bottom of a long
-        // group, and what they are looking at is what follows it.
-        CollapseBar { onToggle(RowEdge.Bottom) }
+        CollapseBar(onToggle)
     }
 }