Parametric axes: min and max vals seem arbitrary

If we take Thick stroke, https://github.com/googlefonts/axisregistry/blob/main/Lib/axisregistry/data/x_opaque.textproto we're limited to -1000-2000. It may make more sense for all parametric axes have a max minValue of -32,767 and a maxValue of 32,767 since the MS Spec mentions that the fvar VariationAxisRecord minValue and maxValue uses the [Fixed](https://learn.microsoft.com/en-us/typography/opentype/spec/otff#data-types:Fixed:~:text=Fixed,point%20number%20(16.16)) datatype

cc @davelab6

Start with Lib/axisregistry/data/x_opaque.textproto and inspect how parametric-axis minValue and maxValue are defined or validated elsewhere in the registry. Compare the current Thick stroke range with the linked OpenType Fixed datatype specification, then confirm the intended bounds across parametric axes and update the relevant data or validation coverage.

Written by the indexing model from the issue text.