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/Jobs/ServerLimitCheckJob.php

@@ -38,7 +38,7 @@ class ServerLimitCheckJob implements ShouldBeEncrypted, ShouldQueue
                     $server->forceDisableServer();
                     $this->team->notify(new ForceDisabled($server));
                 });
-            } elseif ($number_of_servers_to_disable === 0) {
+            } elseif ($number_of_servers_to_disable <= 0) {
                 $servers->each(function ($server) {
                     if ($server->isForceDisabled()) {
                         $server->forceEnableServer();