Fix build error: use fully qualified namespaces for ThisThread and chrono

Co-authored-by: dorkmo <[email protected]>

Author: Copilot

TankAlarm-112025-Client-BluesOpta/TankAlarm-112025-Client-BluesOpta.ino

@@ -46,6 +46,7 @@
   #include <BlockDevice.h>
   #include <mbed.h>
   using namespace mbed;
+  using namespace std::chrono;           // For chrono types (e.g., milliseconds)
   using namespace std::chrono_literals;  // For chrono duration literals (e.g., 100ms)
   #define FILESYSTEM_AVAILABLE
   #define WATCHDOG_AVAILABLE
@@ -673,7 +674,7 @@ void loop() {
   // Sleep to reduce power consumption between loop iterations
   // Use Mbed OS thread sleep for power efficiency - allows CPU to enter low-power states during sleep periods
   #if defined(ARDUINO_OPTA) || defined(ARDUINO_ARCH_MBED)
-    ThisThread::sleep_for(100ms);  // Thread sleep for 100ms - enables power saving
+    mbed::ThisThread::sleep_for(std::chrono::milliseconds(100));  // Thread sleep for 100ms - enables power saving
   #else
     delay(100);  // Fallback for non-Mbed platforms
   #endif