fix(server): handle limit edge case and IPv6 allowlist dedupe

Update server limit enforcement to re-enable force-disabled servers when the
team is at or under its limit (`<= 0` condition).

Improve allowlist validation and matching by:
- supporting IPv6 CIDR mask ranges up to `/128`
- adding IPv6-aware CIDR matching in `checkIPAgainstAllowlist`
- normalizing/deduplicating redundant allowlist entries before saving

Add feature tests for `ServerLimitCheckJob` covering under-limit, at-limit,
over-limit, and no-op scenarios.

app/Rules/ValidIpOrCidr.php

@@ -45,7 +45,10 @@ class ValidIpOrCidr implements ValidationRule
 
                 [$ip, $mask] = $parts;
 
-                if (! filter_var($ip, FILTER_VALIDATE_IP) || ! is_numeric($mask) || $mask < 0 || $mask > 32) {
+                $isIpv6 = filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) !== false;
+                $maxMask = $isIpv6 ? 128 : 32;
+
+                if (! filter_var($ip, FILTER_VALIDATE_IP) || ! is_numeric($mask) || $mask < 0 || $mask > $maxMask) {
                     $invalidEntries[] = $entry;
                 }
             } else {