Address holistic review findings; bump to 1.6.4

[wlaur]

Patch release addressing every finding of the 1.6.3 holistic review. No breaking API removals; the additions and the three input-tightenings below are the whole change.

Documentation

• isinstance_types(x, Q[Dim]) mis-narrows under strict typing. A bare Q[Dim] means Quantity[Dim, Numpy1DArray] to a type checker (the MT default), so a TypeIs narrow of a scalar quantity collapses to Never. The docs now teach Q[Dim, Any], with a warning box in usage.md and a fixed README snippet.
• Q is not an importable name. Every module creates the alias itself (from encomp.units import Quantity as Q). The accidental re-export from encomp.constants is gone, and a test pins that neither encomp.units nor encomp.constants exposes Q.
• Newly documented: encomp's takeover of pint's process-wide application registry and its pinned options; eager fluid-name resolution; tolerant <= / >=; plus_minus() returning a pint.Measurement outside the typed system; the closed set of accepted magnitude and unit types.
• The ~80 lines of hardcoded CoolProp fluid-name listings in CoolPropFluid.__init__ are replaced by the get_global_param_string(...) one-liners plus examples, so they cannot drift from the installed backend.
• Docstrings for the public members that rendered as bare signatures in the Sphinx API reference.

Typing (additive)

• New unit literals — ppm, torr, J/kg, J/g, the g/cm3 family — plus new MassPerNormalVolumeUnits, MolarDensityUnits, MolarSpecificEnthalpyUnits and PowerPerAreaUnits, each with matching Quantity.__new__ overloads.
• New __mul__ / __truediv__ pairs and their inverses: Force / Area = Pressure, Force * Length = Energy, Force * Velocity = Power, Mass / MolarMass = Substance, Substance / Volume = MolarDensity, HeatTransferCoefficient * TemperatureDifference = PowerPerArea, ThermalConductivity / Length = HeatTransferCoefficient. All 27 are verified runtime-sound and inverse-closed by test_overload_conformance.
• Quantity.__getitem__ accepts boolean masks and integer index arrays, so q[q > threshold] — the exact mask type the comparison operators return — now type-checks.
• ideal_gas_density(P, T, M) accepts scalar T / M alongside a vector P.
• New dimensionalities SurfaceTension and MolarSpecificHeatCapacity, and typed accessors Fluid.RHOCRIT / CVMASS / CPMOLAR / CVMOLAR / GAS_CONSTANT / I / TAU.

Behavior changes

• Quantity(True) raises TypeError. bool is an int subclass, so it silently became 1.0 dimensionless. Comparisons against True/False are unaffected.
• Passing a Quantity as the unit raises TypeError, statically and at runtime — its magnitude was silently dropped. .to(qty), where reusing another quantity's unit is the point, still accepts one.
• Fluid("wat3r", ...) raises ValueError at construction rather than at the first property access. The name is resolved against CoolProp once per (backend, fluids) pair; only successful resolutions are cached, so a transient failure is never remembered as "invalid".
• HumidAir.CV / CVha return SpecificHeatPerDryAir / SpecificHeatPerHumidAir, matching C / Cha, instead of falling back to the generic SpecificHeatCapacity.
• Assigning to a pinned registry option (force_ndarray, force_ndarray_like, autoconvert_offset_to_baseunit) logs a warning instead of being discarded in silence. The write is still discarded.
• CoolPropFluid.__getattr__ names the class and points at .search() for an unknown property.

Findings n6 (fluid_name vs name), n10 (warnings.warn in self_check), n11 (repr vs type) and the pint-registry takeover are settled decisions rather than defects; each is now recorded in a code comment so future reviews don't re-flag them.

Note for the release notes: unit spellings that previously inferred UnknownDimensionality now infer their specific dimensionality. That is the helpful direction, but it can surface new type errors in over-annotated user code.

Verification

pytest (741 passed), ruff check + ruff format --check, pyright (strict, 0 errors), pyrefly (0 errors), and the ReadTheDocs-parity Sphinx build (-W) all pass locally. ty is not gating, per project convention.

🤖 Generated with Claude Code