Lamp testbench in Rust around the HPCS 6500

lampbench station / export / label / tm30 / calibrate replace the Python
lamp_station.py, lamp_export.py, label_printer.py, tm30.py and
calibration.py that lived in HPCS6500-py. The driver is a submodule
(HPCS6500/, like mppt-testbench). Workspace crates: tm30 (TM-30-18 port of
colour-science 0.4.7), brother-ql (raster protocol, byte-identical to
brother_ql) and lamp-label (QR + ID labels for the QL-820NWB).

Bundles are byte-identical to lamp_export.py's (golden tests); the station
runs end to end in a test against the simulated instrument.

crates/tm30/examples/bench.rs

@@ -0,0 +1,38 @@
+//! Timing of `tm30::compute` on an HPCS 6500-like input (350 points,
+//! 380-1050 nm). Run with `cargo run -p tm30 --release --example bench`.
+
+use std::time::Instant;
+
+fn main() {
+    // Warm-white LED-like spectrum: blue pump + broad phosphor, on the HPCS
+    // 6500 wavelength grid.
+    let wl: Vec<f64> = (0..350).map(|i| 380.0 + 670.0 * i as f64 / 349.0).collect();
+    let values: Vec<f64> = wl
+        .iter()
+        .map(|&w| {
+            let blue = (-((w - 450.0) / 12.0).powi(2)).exp();
+            let phosphor = 1.6 * (-((w - 600.0) / 70.0).powi(2)).exp();
+            blue + phosphor
+        })
+        .collect();
+
+    let t0 = Instant::now();
+    let first = tm30::compute(&wl, &values).expect("valid spectrum");
+    let cold = t0.elapsed();
+
+    let n = 200;
+    let t1 = Instant::now();
+    let mut rf = 0.0;
+    for _ in 0..n {
+        rf += tm30::compute(&wl, &values).expect("valid spectrum").rf;
+    }
+    let warm = t1.elapsed() / n;
+    assert!((rf / n as f64 - first.rf).abs() < 1e-12);
+
+    println!(
+        "Rf {:.2} Rg {:.2} CCT {:.0} K Duv {:.4}",
+        first.rf, first.rg, first.cct_k, first.duv
+    );
+    println!("first call (parses tables, builds Planckian table): {cold:?}");
+    println!("per call afterwards (mean of {n}): {warm:?}");
+}