Refresh screenshots against a richer, multi-connection fleet

The old screenshots (prod-cluster, 3 nodes, 16 guests) predated Cluster &
SDN, AI Assistant, Bulk Operations, Webhooks, and the accent-color/look
presets added since — none of it showed up in the README. Recaptured every
fleet-data screenshot (dashboard, inventory, topology, storage, backups,
HA, firewall, connections) against a richer fleet: 3 connections (two
clusters, one standalone host), 6 nodes, 26 VMs/LXCs, Ceph + NFS storage.
settings-appearance also refreshed (now shows the amber/rose/teal accents).
setup.png is untouched — it's fleet-data-independent and regenerating it
would mean resetting a real admin account.

Updated the screenshots section caption to match the new fleet size.

README.md

@@ -19,7 +19,7 @@ Fleet control for Proxmox VE — a single dashboard for every cluster and standa
 
 ## Screenshots
 
-Captured against a mock Proxmox cluster (`prod-cluster`: 3 nodes, 16 VMs/LXCs, Ceph + NFS storage) to show the UI populated the way it looks on a real fleet. Click any thumbnail for the full-size image.
+A populated fleet — 3 connections, 6 nodes, 26 VMs/LXCs across two clusters and a standalone host, with Ceph and NFS storage. Click any thumbnail for the full-size image.
 
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