fix: remove stale plugin reference from .claude/settings.json

The enabledPlugins entry referenced beads@beads-marketplace which
does not exist, causing claude doctor to report a plugin error.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.claude/settings.json

@@ -1,7 +1,4 @@
 {
-  "enabledPlugins": {
-    "beads@beads-marketplace": false
-  },
   "hooks": {
     "SessionStart": [
       {