Rewrite the driver in Rust; move the testbench tools out

The repository is now only the HPCS 6500 driver: a Rust library (serial
transport, every protocol command, block parsing, USBPcap captures, a
simulated instrument) and the hpcs6500 CLI with the flags of the former
hpcs6500.py, plus dump/capture for reverse engineering.

The lamp station, lamp export, TM-30, label printer and LED calibration
move to B4L/lamp-testbench. Golden tests pin the Rust output to the Python
driver's: parsed values bit-exact, report text, CSV and number formatting.
The Python driver is at tag python-final.

PROTOCOL.md

@@ -1,6 +1,7 @@
 # HPCS 6500 USB Protocol Reference
 
-Reverse-engineered from USB packet captures of the vendor software.
+Reverse-engineered from USB packet captures of the vendor software. The
+Rust driver in `src/` implements it (`protocol.rs`, `device.rs`, `reading.rs`).
 
 ## Device Overview