feat: add CYD ThermoPro bridge firmware skeleton

Add PlatformIO project for the ESP32-2432S028R that:
- Reads ThermoPro BLE BBQ thermometers via NimBLE-Arduino
- Exposes /api/health, /api/latest, and /api/settings HTTP endpoints
- Serves a captive-portal setup UI and touch dashboard
- Persists WiFi/BLE/settings in NVS via Preferences

Builds cleanly with pio run.

cyd-bridge/src/settings/SettingsManager.cpp

@@ -1,6 +1,7 @@
 #include "SettingsManager.hpp"
 #include <ArduinoJson.h>
 #include <Preferences.h>
+#include <vector>
 
 namespace cyd {
 
@@ -75,7 +76,8 @@ bool SettingsManager::load() {
     settings_.apiEndpoint = doc["apiEndpoint"] | "";
     settings_.apiToken = doc["apiToken"] | "";
     settings_.pollIntervalSec = doc["pollIntervalSec"] | 15;
-    settings_.unit = doc["unit"] | "F";
+    String unit = doc["unit"] | "F";
+    settings_.unit = unit.length() > 0 ? unit.charAt(0) : 'F';
     settings_.deviceId = doc["deviceId"] | "cyd-smoker";
 
     JsonArray names = doc["probeNames"].as<JsonArray>();