v1.16.4 — Background Generator improvements + a real field-visibility fix

Background Generator: hex color input next to every color picker, an optional third gradient stop, and a one-click "Use TheNerdyBox colors" preset using the real brand tokens from @thenerdybox/ui's tokens.css — not guessed from a logo.

Fixed a real bug, found via live testing: setting an element's hidden property was updating the DOM correctly, but a CSS specificity tie meant .field/.field-row class styling silently overrode the browser's own hide behavior — so fields marked hidden kept rendering visually, everywhere this pattern is used across the app, not just in this dialog. Caught by actually driving the running app interactively (Playwright against the dev server), not from reading the code — confirmed fixed the same way.

Full release notes and version history: see the pinned release-notes page (ask if you don't have the link handy).