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/gui/widgets.py

@@ -1075,7 +1075,8 @@ class UartMonitorWindow(ctk.CTkToplevel):
         def _bg_open() -> None:
             try:
                 import serial
-                ser = serial.Serial(self._port, self._baudrate, timeout=1)
+                from serial_monitor import normalize_port
+                ser = serial.Serial(normalize_port(self._port), self._baudrate, timeout=1)
                 ser.close()
                 self.after(0, self._on_open_success)
             except Exception as e: