feat: streamline network panel, conditional self-service, remove IP add endpoints

- Populate network panel from server data response instead of separate API call
- Conditionally render self-service billing panel based on selfServiceMode config
- Pass selfServiceMode to Smarty template vars
- Remove addIPv4, addIPv6, serverIPs client endpoints and UI buttons
- Remove upgrade/downgrade link from resources panel
- Bump cache-busting version to v0.0.20
- Update CHANGELOG.md

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

modules/servers/VirtFusionDirect/lib/ModuleFunctions.php

@@ -531,6 +531,7 @@ class ModuleFunctions extends Module
                     'systemURL' => Database::getSystemUrl(),
                     'serviceStatus' => $params['status'],
                     'serverHostname' => $serverHostname,
+                    'selfServiceMode' => (int) ($params['configoption4'] ?? 0),
                 ],
             ];
         } catch (\Throwable $e) {