feat: add SystemContext class for global system component access

main/common/system_context.h

@@ -0,0 +1,30 @@
+#pragma once
+
+class NetworkHandler;
+class WifiHandler;
+
+/**
+ * @brief System context providing access to global system components
+ */
+class SystemContext {
+public:
+  static SystemContext& instance() {
+    static SystemContext context;
+    return context;
+  }
+
+  void set_network_handler(NetworkHandler* handler) {
+    network_handler_ = handler;
+  }
+
+  NetworkHandler* get_network_handler() const {
+    return network_handler_;
+  }
+
+private:
+  SystemContext() = default;
+  SystemContext(const SystemContext&) = delete;
+  SystemContext& operator=(const SystemContext&) = delete;
+
+  NetworkHandler* network_handler_ = nullptr;
+};