fix: ConnectionTracker == typo and Thread $process init type

- ConnectionTracker::getCapacity: `$rSettings['split_by'] == 'guar_band';` was a
  discarded comparison (==) where an assignment (=) was intended — the proxy
  maxclients→guar_band override never happened.
- Thread::__construct: initialised $process (typed resource|null) to int 0;
  set it to null to match the property type (and its own default).

src/core/Process/Thread.php

@@ -42,7 +42,7 @@ class Thread {
      * Initialize an empty process-thread state.
      */
     public function __construct() {
-        $this->process = 0;
+        $this->process = null;
         $this->buffer = '';
         $this->pipes = (array) null;
         $this->output = '';

src/domain/Stream/ConnectionTracker.php

@@ -56,7 +56,7 @@ class ConnectionTracker {
 		$rRedis = RedisManager::instance();
 		$rFile = ($rProxy ? 'proxy_capacity' : 'servers_capacity');
 		if ($rSettings['redis_handler'] && $rProxy && $rSettings['split_by'] == 'maxclients') {
-			$rSettings['split_by'] == 'guar_band';
+			$rSettings['split_by'] = 'guar_band';
 		}
 
 		if ($rSettings['redis_handler'] && $rRedis) {