fix(cli): tighten mosaic icon to compact 3×3 grid

- Use half-block chars (▐█ █▌) for outer tiles to reduce width
- Center pink tile fits snugly between the four corners
- Matches the mosaic windmill proportions from the web UI

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

@@ -24,7 +24,7 @@ function formatContextWindow(n: number): string {
 }
 
 /**
- * Mosaic windmill icon — 4 colored tiles + pink center
+ * Mosaic windmill icon — 4 colored tiles + pink center in 3×3 grid
  * Colors from the Mosaic brand:
  *   TL: blue (#2f80ff)  TR: purple (#8b5cf6)
  *   BL: amber (#f59e0b) BR: teal (#14b8a6)
@@ -34,19 +34,16 @@ function MosaicIcon() {
   return (
     <Box flexDirection="column" marginRight={1}>
       <Text>
-        <Text color="#2f80ff">██</Text>
-        <Text> </Text>
-        <Text color="#8b5cf6">██</Text>
+        <Text color="#2f80ff">▐█</Text>
+        <Text color="#8b5cf6">█▌</Text>
       </Text>
       <Text>
         <Text> </Text>
         <Text color="#ec4899">██</Text>
-        <Text> </Text>
       </Text>
       <Text>
-        <Text color="#f59e0b">██</Text>
-        <Text> </Text>
-        <Text color="#14b8a6">██</Text>
+        <Text color="#f59e0b">▐█</Text>
+        <Text color="#14b8a6">█▌</Text>
       </Text>
     </Box>
   );