feat(gui): add FT601Connection class, USB interface selection in V65/V7

- Add FT601Connection in radar_protocol.py using ftd3xx library with
  proper setChipConfiguration re-enumeration handling (close, wait 2s,
  re-open) and 4-byte write alignment
- Add USB Interface dropdown to V65 Tk GUI (FT2232H default, FT601 option)
- Add USB Interface combo to V7 PyQt dashboard with Live/File mode toggle
- Fix mock frame_start bit 7 in both FT2232H and FT601 connections
- Use FPGA range data from USB packets instead of recomputing in Python
- Export FT601Connection from v7/hardware.py and v7/__init__.py
- Add 7 FT601Connection tests (91 total in test_GUI_V65_Tk.py)

9_Firmware/9_3_GUI/v7/hardware.py

@@ -25,6 +25,7 @@ if USB_AVAILABLE:
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
 from radar_protocol import (  # noqa: F401 — re-exported for v7 package
     FT2232HConnection,
+    FT601Connection,
     RadarProtocol,
     Opcode,
     RadarAcquisition,