Wires up the remaining editor sections (theme, header, footer, homepage,
widgets, features, languages, navigation) with the description text and
dropdown UX started for General/Branding:
- Every enum-backed field is now a <select> with a description per option,
not free text: theme.mode, the new site-wide layout.type (previously had
no editor at all - added to the Theme section, and added to that
section's reset-scope), homepage section layout.strategy, and
catalog.navigationMode (also previously unedited, added to Features).
- Every other field (colors, header toggles, footer contact/company fields,
widget props, feature flags, language add, nav link label/url/visible)
gets a one-line plain-language description under its label via the new
*Desc i18n keys (en/ru/hy) prepared earlier.
- Genuinely open text (widget layout variant strings, JSON props) stays
free text, description-only, per the existing widgetLayoutDesc/widgetJsonDesc
wording - not force-fit into a dropdown.
Verified: tsc --noEmit and ng build both clean.
