fix(tui): idle good-vibes heart no longer blanks the input's last cell

The heart was rendered as a literal space when inactive. Because it's
absolutely positioned at right:0 inside the composer row, that blank
still overpainted the rightmost input cell. On wrapped 2-line drafts,
editing near the boundary made the final visible character appear to
jump in/out as it crossed the overpainted column.

When inactive, render nothing; only mount the heart while it's actually
animating.

ui-tui/src/components/appChrome.tsx

@@ -156,7 +156,11 @@ export function GoodVibesHeart({ tick, t }: { tick: number; t: Theme }) {
     return () => clearTimeout(id)
   }, [t.color.amber, tick])
 
-  return <Text color={color}>{active ? '♥' : ' '}</Text>
+  if (!active) {
+    return null
+  }
+
+  return <Text color={color}>♥</Text>
 }
 
 export function StatusRule({