feat(inquirerer): add Claude Code-style UI with welcome box and conversation markers

- Add welcome box with rounded corners and two-column layout
- Add conversation markers: > for user, ⏺ for assistant
- Add animated spinner for streaming indicator
- Use full-width separators
- Add ↵ send hint in input area
- Fix UP/DOWN arrows to navigate multiline input with preferredCol tracking
- Add string-width dependency for proper display width calculations

Author: pyramation

packages/inquirerer/package.json

@@ -39,6 +39,7 @@
     "find-and-require-package-json": "workspace:*",
     "js-yaml": "^4.1.0",
     "minimist": "^1.2.8",
+    "string-width": "4.2.3",
     "yanse": "workspace:*"
   },
   "keywords": [],