Initial commit: Prodigit 3366G DC Electronic Load RS-232 driver and CLI

Python package for controlling the Prodigit 3366G (600V/420A/6kW) over
RS-232 serial. Includes driver with full command support (CC/CR/CV/CP
modes, measurements, battery test, OCP/OPP, dynamic mode, limits) and
CLI tool with identify, measure, monitor, live graph, and raw send.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -0,0 +1,79 @@
+# Prodigit 3366G DC Electronic Load
+
+Python RS-232 control tools for the Prodigit 3366G High Power DC Electronic Load (600V, 420A, 6000W).
+
+## Setup
+
+```bash
+uv sync
+```
+
+## Quick Start
+
+```bash
+# Identify the instrument
+prodigit identify
+
+# Take a single measurement
+prodigit measure
+
+# Monitor continuously (Ctrl+C to stop)
+prodigit monitor --interval 1.0 --output data.csv
+
+# Live graph
+prodigit live --interval 0.5
+
+# Set CC mode at 10A
+prodigit set CC 10.0
+
+# Turn load on/off
+prodigit load on
+prodigit load off
+
+# Send raw command
+prodigit send "MODE?"
+prodigit send "CC CURR:HIGH 5.0"
+```
+
+## Serial Connection
+
+Default: **COM1**, 9600 baud, 8N1, RTS/CTS hardware flow control.
+
+```bash
+# Use a different port or baud rate
+prodigit -p COM3 -b 115200 identify
+```
+
+## Python API
+
+```python
+from prodigit3366g import Prodigit3366G
+
+with Prodigit3366G("COM1", baudrate=9600) as load:
+    load.remote()
+    load.set_mode("CC")
+    load.set_cc_current(10.0)
+    load.load_on()
+
+    result = load.measure_all()
+    print(f"V={result.voltage:.3f}V  I={result.current:.3f}A  P={result.power:.3f}W")
+
+    load.load_off()
+```
+
+## Modes
+
+| Mode | Command | Description |
+|------|---------|-------------|
+| CC | `prodigit set CC <amps>` | Constant Current (0-420A) |
+| CR | `prodigit set CR <ohms>` | Constant Resistance |
+| CV | `prodigit set CV <volts>` | Constant Voltage (0-600V) |
+| CP | `prodigit set CP <watts>` | Constant Power (0-6000W) |
+
+## 3366G Specifications
+
+| Parameter | Range 1 | Range 2 (turbo) |
+|-----------|---------|-----------------|
+| Power | 0-6kW | 0-9kW |
+| Current | 0-420A | 0-630A |
+| Voltage | 0-600V | 0-600V |