fix: use xsct (not Vivado) for JTAG check + normalize COM>=10 ports on Windows

**JTAG check**: Switch from Vivado to xsct
- xsct is already proven to work (JTAG reboot succeeds)
- Much lighter than Vivado (no GUI infrastructure / open_hw_manager)
- Uses -eval inline TCL: connect; targets; disconnect; quit
- Removes dead tempfile/Path/os imports

**Windows COM port**: Add normalize_port() to serial_monitor.py
- COM ports >= 10 require NT namespace prefix (\.\COM11)
- Without it: PermissionError(13, '拒绝访问。')
- Applied at all 7 call sites: serial_monitor (5), reboot_manager, widgets

src/reboot_manager.py

@@ -125,9 +125,10 @@ def reboot_via_serial(
 
     try:
         import serial
+        from serial_monitor import normalize_port
 
         with serial.Serial(
-            config.serial_port,
+            normalize_port(config.serial_port),
             config.serial_baudrate,
             timeout=5,
         ) as ser: