refactor: extract BlockButtons component from InstallationGuide

Move button rendering logic (URL validation, copy handler, icon
components) into a dedicated BlockButtons component. Remove
duplicate getLocalizedText/getBaseTranslation helpers from
Connection page controller.

src/components/connection/blocks/index.ts

@@ -2,4 +2,5 @@ export { CardsBlock } from './CardsBlock';
 export { TimelineBlock } from './TimelineBlock';
 export { AccordionBlock } from './AccordionBlock';
 export { MinimalBlock } from './MinimalBlock';
+export { BlockButtons } from './BlockButtons';
 export type { BlockRendererProps } from './types';