Restore tui and autoUpdatesChannel settings

Both were present in the live config on the Windows machine but absent from
the tracked settings.json, so install.sh silently dropped them:

  tui: fullscreen        -- full-screen TUI rather than inline
  autoUpdatesChannel: latest

Neither is machine-specific, so track them for all machines.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

settings.json

@@ -40,6 +40,8 @@
   },
   "theme": "dark",
   "verbose": false,
+  "tui": "fullscreen",
   "preferredNotifChannel": "terminal_bell",
-  "autoUpdaterStatus": "enabled"
+  "autoUpdaterStatus": "enabled",
+  "autoUpdatesChannel": "latest"
 }