Settings as panels, the way the portal does it

Four tabs over three cards was navigation for its own sake, and the two shells
disagreed about what a settings screen looks like. It is one grid of cards now,
matching the portal: the account card carries changing a password and deleting
the account in its footer, appearance is a card with one row, and remote access
— an operator's concern, not a personal preference — is a card of its own for a
superuser.

SettingRow, alert-dialog and UserAvatar come across from the portal, so an
account renders the same face in both shells.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/package.json

@@ -39,6 +39,7 @@
     "@tanstack/react-table": "^8.21.3",
     "@xyflow/react": "^12.11.3",
     "axios": "1.13.2",
+    "boring-avatars": "^2.0.4",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "cmdk": "^1.1.1",