fix(claude): remove hardcoded model override from settings

Let the model be determined by context/defaults rather than forcing
opus globally.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

claude/settings.json

@@ -90,7 +90,6 @@
       "Read(./secrets/**)"
     ]
   },
-  "model": "opus",
   "statusLine": {
     "type": "command",
     "command": "~/.claude/statusline.sh",