refactor(net): unique_ptr for connection-lifecycle objects (#11459)

- WiFiServerAPI/ethServerAPI apiPort and ethApiServer's listener are
  create/destroy cycles that repeat across WiFi teardown and W5500
  chip resets; the manual delete+null bookkeeping becomes reset().
  (ethTlsApiServer's listener is left for a follow-up: that file is
  already touched by the partial-init fix PR and converting it here
  would conflict.)

- ContentHandler::handleFormUpload held its body parser raw with
  delete on four separate exit paths of a per-request handler; any
  future early return was a silent leak. unique_ptr removes all four.

- The portduino ch341Hal global becomes unique_ptr. The LoRa-error
  recovery loop's delete/null/new sequence was correct only by
  hand-preserved ordering; it becomes reset()/make_unique. RadioLibHAL
  keeps a non-owning raw pointer, as before.

No behavior change.

src/platform/portduino/PortduinoGlue.cpp

@@ -62,7 +62,7 @@ portduino_config_struct portduino_config;
 portduino_status_struct portduino_status;
 std::ofstream traceFile;
 std::ofstream JSONFile;
-Ch341Hal *ch341Hal = nullptr;
+std::unique_ptr<Ch341Hal> ch341Hal;
 char *configPath = nullptr;
 char *optionMac = nullptr;
 bool verboseEnabled = false;
@@ -325,8 +325,8 @@ void portduinoSetup()
     {
         extern void wasm_config_apply();
         wasm_config_apply();
-        ch341Hal =
-            new Ch341Hal(0, portduino_config.lora_usb_serial_num, portduino_config.lora_usb_vid, portduino_config.lora_usb_pid);
+        ch341Hal = std::make_unique<Ch341Hal>(0, portduino_config.lora_usb_serial_num, portduino_config.lora_usb_vid,
+                                              portduino_config.lora_usb_pid);
     }
     return;
 #endif
@@ -650,8 +650,8 @@ void portduinoSetup()
     uint8_t dmac[6] = {0};
     if (portduino_config.lora_spi_dev == "ch341") {
         try {
-            ch341Hal = new Ch341Hal(0, portduino_config.lora_usb_serial_num, portduino_config.lora_usb_vid,
-                                    portduino_config.lora_usb_pid);
+            ch341Hal = std::make_unique<Ch341Hal>(0, portduino_config.lora_usb_serial_num, portduino_config.lora_usb_vid,
+                                                  portduino_config.lora_usb_pid);
         } catch (std::exception &e) {
             std::cerr << e.what() << std::endl;
             std::cerr << "Could not initialize CH341 device!" << std::endl;

src/platform/portduino/PortduinoGlue.h

@@ -1,6 +1,7 @@
 #pragma once
 #include <fstream>
 #include <map>
+#include <memory>
 #include <unistd.h>
 #include <unordered_map>
 #include <vector>
@@ -64,7 +65,7 @@ struct pinMapping {
 extern std::ofstream traceFile;
 extern std::ofstream JSONFile;
 
-extern Ch341Hal *ch341Hal;
+extern std::unique_ptr<Ch341Hal> ch341Hal;
 int initGPIOPin(int pinNum, const std::string &gpioChipname, int line);
 bool loadConfig(const char *configPath);
 static bool ends_with(std::string_view str, std::string_view suffix);