'Value kind' field in create-series form is redundant with Parameter and can be set incorrectly

[jeandavidt]

Problem

The Value kind field (e.g. "Scalar") in the "Create new series" form is presented as a free user choice, but it's actually a property of the selected Parameter — a given parameter only ever has one valid value kind.

Steps to reproduce:

1. Open "Create new series", pick a Parameter (e.g. "TSS concentration").
2. Note Value kind is still an independently-editable required dropdown, defaulted to "Scalar".

Expected: Value kind should be derived automatically from the selected Parameter (read-only display, or removed from the form entirely), not user-editable.

Actual: It's editable, so a user could pick a Value kind inconsistent with the Parameter, silently corrupting the series' semantics.