fix: support IPv6 addresses in ping monitor

## Changes
- Fixed ping host sanitization regex that stripped everything after
  the first colon, which destroyed IPv6 addresses like 2001:db8::1
- New regex properly handles bracketed IPv6 ([::1]:port), bare IPv6,
  and IPv4/hostname:port formats separately

## Closes
Fixes #3053

server/src/service/infrastructure/networkService.ts

@@ -261,7 +261,8 @@ class NetworkService implements INetworkService {
 			const sanitizedHost = rawUrl
 				.replace(/^https?:\/\//, "")
 				.replace(/\/.*$/, "")
-				.replace(/:.*/, "");
+				.replace(/^\[(.+)\](?::.*)?$/, "$1") // Extract IPv6 from brackets, strip port
+				.replace(/^([^[\]:]+):(\d+)$/, "$1"); // Strip port from IPv4/hostname only
 			const { response, error } = await this.timeRequest(() => this.ping.promise.probe(sanitizedHost));
 
 			if (!response) {