Migrate the remaining QAtlas quantity tags

[sotashimozono]

v0.1 ported the abstract hierarchy + a curated tag set (see src/core/quantities.jl header). The remaining ~45 tags (NMR family, Loschmidt/DQPT, entanglement measures, correlation/structure-factor families with their {M} mode parameters, velocities, CFT data, …) migrate here incrementally as QAtlas adopts this package (QAtlasHub/QAtlas.jl#729) — driven by need, not bulk-copied. Each migration must move the tag's docstring and any trait methods (component, granularity) with it.

[sotashimozono]

Status: QAtlas-adoption-gated (ongoing, not standalone-actionable). The remaining quantity tags migrate INCREMENTALLY as QAtlas adopts AbstractQAtlas (the AbstractFFTs→FFTW idiom) — each tag lands here when a relation or a QAtlas consumer actually needs it, never a bulk copy (per the core/quantities.jl header). Recent additions already followed this (SpinStructureFactor #115, DynamicalSpinStructureFactor #117, the grand-canonical GrandPotential/ParticleNumber sector). No blocker; it advances with QAtlas integration rather than as a discrete task.