v1.5.1: scope-switch fix, light-theme instance-props fix, Pro gating

Fixes

• CSS scope switch: you can now add rules to a scope the class was not already in. Previously, when a class had saved rules in only one scope, Builderius forced the editor back to that scope, so switching to the empty Global or Template scope to start a rule there was ignored (the Selectors tab was the only way in). The scope bar and scope guard now re-point the editor at the chosen scope, so the first declaration saves where you asked. Reported upstream to Builderius.
• Light theme: a placed component's instance property labels no longer render black-on-black. The label rows kept a native dark surface while the text was remapped for the light theme; both now use the theme tokens.

Changes

• The CSS code editor, CSS scope bar and CSS scope guard now require Builderius Pro, since they depend on the Pro CSS code editor and template-specific CSS. When Pro is inactive these features stay off (the native CSS-mode icon is left in place), their settings rows are disabled with a note, and your saved choices are preserved for when Pro is active again.