Enhance CLI actions and default handling

Add timed follow, src/lib upload helpers, and store default startup pattern under default key.

Made-with: Cursor

device.py

@@ -208,12 +208,21 @@ class DeviceConnection:
         except Exception as e:
             raise TransportError(f"Failed to reset device: {e}") from e
     
-    def follow_output(self):
-        """Follow device output continuously (like tail -f)."""
+    def follow_output(self, duration=None):
+        """
+        Follow device output (like tail -f).
+        
+        Args:
+            duration: Optional number of seconds to follow output for. If None,
+                      follow indefinitely until interrupted.
+        """
         # Use direct serial connection like dev.py does
+        start_time = time.time()
         try:
             with serial.Serial(self.device, baudrate=115200) as ser:
                 while True:
+                    if duration is not None and (time.time() - start_time) >= duration:
+                        break
                     if ser.in_waiting > 0:
                         data = ser.readline().decode('utf-8', errors='replace').strip()
                         if data: