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No CCS calibration for TWIMS drift time - only raw drift_time_ms is exposed #10

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@Nathan-D-R

Found in a cross-vendor parity audit of the OpenMassSpec stack.

Encoding-B (SYNAPT traveling-wave IMS) spectra expose drift_time_ms per peak (ImsSpectrum, both Rust and Python surfaces), but there's no conversion to collision cross section (CCS) anywhere in the crate - confirmed zero hits for "ccs"/"CCS"/"cross section" in crates/openwraw/src/.

Raw drift time isn't directly comparable across instruments/conditions the way CCS is, so this is the difference between "has IMS data" and "IMS data usable for the kind of cross-instrument/cross-run comparison people reach for TWIMS data to do in the first place." Waters' TWIMS CCS calibration typically needs a calibrant-run correction (traveling-wave height/velocity, gas, drift cell length) rather than a closed-form physical formula, so this is more involved than a lookup - worth scoping as its own investigation into what calibration inputs are actually available in the .raw bundle (if any) versus requiring an external calibration file.

Related: Sigilweaver/OpenTimsTDF has the equivalent gap for Bruker 1/K0 (no issue filed there yet as of this audit - CCS is unimplemented for both IMS-capable vendors in the stack).

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