Add timeout to calibrateDelay to prevent CI hangs

The calibration shSync calls used delay=0 with no timeout, which could
block indefinitely if prompt detection fails (e.g. on slow SSH containers
in CI where output arrives in multiple TCP fragments). Add a 10-second
timeout per calibration call and gracefully fall back to the default
delay if any call times out.

Author: stalep

qDup-core/src/main/java/io/hyperfoil/tools/qdup/shell/AbstractShell.java

@@ -357,14 +357,31 @@ private void calibrateDelay() {
         int originalDelay = getDelay();
         setDelay(0);
 
+        // Use a timeout for calibration shSync calls to avoid hanging if prompt
+        // detection fails with delay=0 (e.g. slow SSH containers in CI)
+        int timeoutSeconds = 10;
+
         // Warmup: discard first measurement to avoid SSH channel setup overhead
         calibrating = true;
-        shSync("echo qdup_ping");
+        SyncResponse warmup = shSync("echo qdup_ping", null, timeoutSeconds);
+        if (warmup.timedOut()) {
+            // Shell is too slow or unresponsive — keep default delay
+            calibrating = false;
+            setDelay(originalDelay);
+            logger.warnf("%s calibration warmup timed out, keeping default delay %dms", getName(), originalDelay);
+            return;
+        }
 
         long maxLatencyNs = 0;
         int samples = 3;
         for (int i = 0; i < samples; i++) {
-            shSync("echo qdup_ping");
+            SyncResponse resp = shSync("echo qdup_ping", null, timeoutSeconds);
+            if (resp.timedOut()) {
+                calibrating = false;
+                setDelay(originalDelay);
+                logger.warnf("%s calibration sample %d timed out, keeping default delay %dms", getName(), i, originalDelay);
+                return;
+            }
             if (lastCalibrationNs > maxLatencyNs) {
                 maxLatencyNs = lastCalibrationNs;
             }