[BT] Reset BTProcessLock when immediateBTAction can't take the device semaphore (#2314)

immediateBTAction() sets BTProcessLock=true and stops the scan before an
outbound BLE action, and resets it on the success path and the
"BLE busy" path — but the branch where semaphoreCreateOrUpdateDevice
can't be taken left it true. Under scan contention that wedges the BLE
scanner/connect subsystem until a restart (same BTProcessLock-mishandling
family as the long-uptime NimBLE scanner hang). Reset it on that branch
too.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

main/gatewayBT.cpp

@@ -1692,6 +1692,10 @@ void immediateBTAction(void* pvParameters) {
         xSemaphoreGive(semaphoreCreateOrUpdateDevice);
       } else {
         THEENGS_LOG_ERROR(F("CreateOrUpdate Semaphore NOT taken" CR));
+        // Release the process lock we took above; otherwise a transient
+        // semaphore-contention failure here leaves BTProcessLock=true and
+        // wedges the BLE scanner/connect subsystem until a restart.
+        BTProcessLock = false;
       }
 
       // If we stopped the scheduled connect for this action, do the scheduled now