Port upstream security fixes and features from ngoduykhanh/wireguard-ui

- Escape HTML in client list and wake-on-LAN names to prevent XSS
- Log successful/failed login attempts with remote address
- Fix leading-comma bug in AllowedIPs template when only extra allowed IPs are set
- Add PreUp script support for server interfaces (alongside existing PostUp/PreDown/PostDown)
- Fix endpoint parsing to support IPv6 addresses (upstream PR #223)

Cherry-picked from upstream PRs #656, #653, #680, #673, #223.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

templates/wg.conf

@@ -8,6 +8,7 @@ Address = {{$first :=true}}{{range .serverConfig.Interface.Addresses }}{{if $fir
 ListenPort = {{ .serverConfig.Interface.ListenPort }}
 PrivateKey = {{ .serverConfig.KeyPair.PrivateKey }}
 {{if .globalSettings.MTU}}MTU = {{ .globalSettings.MTU }}{{end}}
+PreUp = {{ .serverConfig.Interface.PreUp }}
 PostUp = {{ .serverConfig.Interface.PostUp }}
 PreDown = {{ .serverConfig.Interface.PreDown }}
 PostDown = {{ .serverConfig.Interface.PostDown }}
@@ -27,7 +28,14 @@ Table = {{ .globalSettings.Table }}
 [Peer]
 PublicKey = {{ .Client.PublicKey }}
 {{if .Client.PresharedKey}}PresharedKey = {{ .Client.PresharedKey }}{{end}}
-AllowedIPs = {{$first :=true}}{{range .Client.AllocatedIPs }}{{if $first}}{{$first = false}}{{else}},{{end}}{{.}}{{end}}{{range .Client.ExtraAllowedIPs }},{{.}}{{end}}
+AllowedIPs = {{ $first := true }}
+{{- range .Client.AllocatedIPs -}}
+  {{- if not $first}}, {{ end -}}{{ . -}}{{ $first = false -}}
+{{- end -}}
+{{- range .Client.ExtraAllowedIPs -}}
+  {{- if not $first}}, {{ end -}}{{ . -}}{{ $first = false -}}
+{{- end }}
+{{"\n"}}
 {{if $.globalSettings.PersistentKeepalive}}PersistentKeepalive = {{ $.globalSettings.PersistentKeepalive }}{{end}}
 {{if .Client.Endpoint}}Endpoint = {{ .Client.Endpoint }}{{end}}
 {{end}}{{end}}