fix(paint): continuous backgroundColor across wrapped text lines

- Wrap each text line with applyChalk(bgProps) after wrapText so
  background color is reapplied on every wrapped line (wrap-ansi
  doesn't carry ANSI state across line breaks)
- Add wrapped-text backgroundColor regression test
- Fix typo: color=" cyan" → color="cyan" in example
- Add FORCE_COLOR=3 debugging tip to AGENTS.md

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

examples/basic-template/src/App.vue

@@ -13,7 +13,7 @@ useInput((input) => {
 </script>
 
 <template>
-  <Box flexDirection="column" :paddingX="1">
+  <Box backgroundColor="blue" borderStyle="round" width="20">
     <Text bold color="cyan">vue-tui basic (template)</Text>
     <Text dimColor>Try editing Counter.vue or App.vue</Text>
     <Text dimColor>Press c=toggle clock, q=quit</Text>