Reskin product modal for Minimal Light (styling only)

Product modal's inline-styled elements (typography, stepper, Add button) now branch on active_template() to use Minimal Light's palette when active — Khana Khazana's values are completely unchanged. Attribute pills and modal shell styled via the existing body.dd-tpl-minimal-light CSS scope. Zero changes to modal logic, event handlers, state, or data flow — verified against the full "don't touch" list from the prior investigation.