fix(tui): address copilot round 3 on #14145

- appLayout.tsx: restore the 1-row placeholder when `showStickyPrompt`
  is false. Dropping it saved a row but the composer height shifted by
  one as the prompt appeared/disappeared, jumping the input vertically
  on scroll.
- useInputHandlers: gateway.rpc (from useMainApp) already catches errors
  with its own sys() message and resolves to null. The previous `.catch`
  was dead code and on RPC failures the user saw both 'error: ...' (from
  rpc) and 'failed to toggle yolo'. Drop the catch and gate 'failed to
  toggle yolo' on a non-null response so null (= rpc already spoke)
  stays silent.

ui-tui/src/app/useInputHandlers.ts

@@ -384,10 +384,21 @@ export function useInputHandlers(ctx: InputHandlerContext): InputHandlerResult {
         return void actions.sys('yolo needs an active session')
       }
 
-      return void gateway
-        .rpc<ConfigSetResponse>('config.set', { key: 'yolo', session_id: live.sid })
-        .then(r => actions.sys(r?.value === '1' ? 'yolo on' : r?.value === '0' ? 'yolo off' : 'failed to toggle yolo'))
-        .catch(() => actions.sys('failed to toggle yolo'))
+      // gateway.rpc swallows errors with its own sys() message and resolves to null,
+      // so we only speak when it came back with a real shape. null = rpc already spoke.
+      return void gateway.rpc<ConfigSetResponse>('config.set', { key: 'yolo', session_id: live.sid }).then(r => {
+        if (r?.value === '1') {
+          return actions.sys('yolo on')
+        }
+
+        if (r?.value === '0') {
+          return actions.sys('yolo off')
+        }
+
+        if (r) {
+          actions.sys('failed to toggle yolo')
+        }
+      })
     }
 
     if (key.tab && cState.completions.length) {

ui-tui/src/components/appLayout.tsx

@@ -173,12 +173,14 @@ const ComposerPane = memo(function ComposerPane({
         </Text>
       )}
 
-      {status.showStickyPrompt && (
+      {status.showStickyPrompt ? (
         <Text color={ui.theme.color.dim} wrap="truncate-end">
           <Text color={ui.theme.color.label}>↳ </Text>
 
           {status.stickyPrompt}
         </Text>
+      ) : (
+        <Text> </Text>
       )}
 
       <StatusRulePane at="top" composer={composer} status={status} />