feat(cli): simplify top bar — title + host only

- Show 'Mosaic Stack TUI' on left, gateway host on right
- Remove connection status from top bar (lives in footer)
- Remove model/conversation from top bar (lives in footer)

packages/cli/src/tui/components/top-bar.tsx

@@ -2,54 +2,19 @@ import React from 'react';
 import { Box, Text } from 'ink';
 
 export interface TopBarProps {
-  connected: boolean;
-  connecting: boolean;
   gatewayUrl: string;
-  conversationId?: string;
-  modelName: string | null;
 }
 
-export function TopBar({
+export function TopBar({ gatewayUrl }: TopBarProps) {
-  connected,
-  connecting,
-  gatewayUrl,
-  conversationId,
-  modelName,
-}: TopBarProps) {
-  const indicator = connected ? '●' : '○';
-  const indicatorColor = connected ? 'green' : connecting ? 'yellow' : 'red';
-
-  const statusLabel = connected ? 'connected' : connecting ? 'connecting' : 'disconnected';
-
   // Strip protocol for compact display
   const host = gatewayUrl.replace(/^https?:\/\//, '');
 
   return (
     <Box borderStyle="single" borderColor="gray" paddingX={1} justifyContent="space-between">
-      <Box>
       <Text bold color="blue">
-          mosaic
+        Mosaic Stack TUI
       </Text>
-        <Text> </Text>
+      <Text dimColor>{host}</Text>
-        <Text color={indicatorColor}>{indicator}</Text>
-        <Text dimColor> {statusLabel}</Text>
-        <Text dimColor> · {host}</Text>
-      </Box>
-      <Box>
-        {modelName && (
-          <>
-            <Text dimColor>model: </Text>
-            <Text color="magenta">{modelName}</Text>
-            <Text> </Text>
-          </>
-        )}
-        {conversationId && (
-          <>
-            <Text dimColor>conv: </Text>
-            <Text>{conversationId.slice(0, 8)}</Text>
-          </>
-        )}
-      </Box>
     </Box>
   );
 }