refactor(tui): wrap progress panel + streaming body in StreamingAssistant

Two improvements:

1. The progress ToolTrail and the streaming MessageLine were two
   sibling JSX blocks in appLayout with hand-rolled margin glue
   between them. Extracted into `<StreamingAssistant>`, a single
   component that owns both the trail and the streaming body plus
   the 1-row gap between them. appLayout just hands it `progress`
   and theme; the layout logic lives in one place, matching the
   mental model that these two pieces are one live assistant turn.

2. Thinking token label was hidden when `reasoningTokens === 0` even
   if the live reasoning text was already populated (the
   scheduleReasoning timer hadn't ticked, or the model sent no
   reasoning but the text was coming in via reasoning.delta).
   Changed the tokenCount fallback from `reasoningTokens !==
   undefined ? reasoningTokens : estimate` to `reasoningTokens > 0 ?
   ... : estimate` so the label appears the moment text exists.

ui-tui/src/components/appLayout.tsx

@@ -2,10 +2,12 @@ import { AlternateScreen, Box, NoSelect, ScrollBox, Text } from '@hermes/ink'
 import { useStore } from '@nanostores/react'
 import { memo } from 'react'
 
-import type { AppLayoutProps } from '../app/interfaces.js'
+import type { AppLayoutProgressProps, AppLayoutProps } from '../app/interfaces.js'
 import { $isBlocked } from '../app/overlayStore.js'
 import { $uiState } from '../app/uiStore.js'
 import { PLACEHOLDER } from '../content/placeholders.js'
+import type { Theme } from '../theme.js'
+import type { DetailsMode } from '../types.js'
 
 import { GoodVibesHeart, StatusRule, StickyPromptTracker, TranscriptScrollbar } from './appChrome.js'
 import { AppOverlays } from './appOverlays.js'
@@ -15,6 +17,58 @@ import { QueuedMessages } from './queuedMessages.js'
 import { TextInput } from './textInput.js'
 import { ToolTrail } from './thinking.js'
 
+const StreamingAssistant = memo(function StreamingAssistant({
+  busy,
+  cols,
+  compact,
+  detailsMode,
+  progress,
+  t
+}: {
+  busy: boolean
+  cols: number
+  compact?: boolean
+  detailsMode: DetailsMode
+  progress: AppLayoutProgressProps
+  t: Theme
+}) {
+  if (!progress.showProgressArea && !progress.showStreamingArea) return null
+
+  return (
+    <Box flexDirection="column">
+      {progress.showProgressArea && (
+        <Box flexDirection="column" marginBottom={progress.showStreamingArea ? 1 : 0}>
+          <ToolTrail
+            activity={progress.activity}
+            busy={busy}
+            detailsMode={detailsMode}
+            reasoning={progress.reasoning}
+            reasoningActive={progress.reasoningActive}
+            reasoningStreaming={progress.reasoningStreaming}
+            reasoningTokens={progress.reasoningTokens}
+            subagents={progress.subagents}
+            t={t}
+            tools={progress.tools}
+            toolTokens={progress.toolTokens}
+            trail={progress.turnTrail}
+          />
+        </Box>
+      )}
+
+      {progress.showStreamingArea && (
+        <MessageLine
+          cols={cols}
+          compact={compact}
+          detailsMode={detailsMode}
+          isStreaming
+          msg={{ role: 'assistant', text: progress.streaming }}
+          t={t}
+        />
+      )}
+    </Box>
+  )
+})
+
 const TranscriptPane = memo(function TranscriptPane({
   actions,
   composer,
@@ -55,35 +109,15 @@ const TranscriptPane = memo(function TranscriptPane({
 
           {transcript.virtualHistory.bottomSpacer > 0 ? <Box height={transcript.virtualHistory.bottomSpacer} /> : null}
 
-          {progress.showProgressArea && (
-            <ToolTrail
-              activity={progress.activity}
-              busy={ui.busy}
-              detailsMode={ui.detailsMode}
-              reasoning={progress.reasoning}
-              reasoningActive={progress.reasoningActive}
-              reasoningStreaming={progress.reasoningStreaming}
-              reasoningTokens={progress.reasoningTokens}
-              subagents={progress.subagents}
-              t={ui.theme}
-              tools={progress.tools}
-              toolTokens={progress.toolTokens}
-              trail={progress.turnTrail}
-            />
-          )}
+          <StreamingAssistant
+            busy={ui.busy}
+            cols={composer.cols}
+            compact={ui.compact}
+            detailsMode={ui.detailsMode}
+            progress={progress}
+            t={ui.theme}
+          />
 
-          {progress.showStreamingArea && (
-            <Box flexDirection="column" marginTop={progress.showProgressArea ? 1 : 0}>
-              <MessageLine
-                cols={composer.cols}
-                compact={ui.compact}
-                detailsMode={ui.detailsMode}
-                isStreaming
-                msg={{ role: 'assistant', text: progress.streaming }}
-                t={ui.theme}
-              />
-            </Box>
-          )}
         </Box>
       </ScrollBox>