feat: add landing page copy and styles for English and Amharic versions

- Introduced `landing-copy.ts` containing text for the public landing page, supporting both English and Amharic languages.
- Added `landing.css` for styling the landing page, ensuring scoped styles to prevent conflicts with other app styles.
- Implemented smooth scrolling and animations for a better user experience.

apps/backoffice/src/app/i18n/locales/am.ts

@@ -1,6 +1,9 @@
+import { landingAm } from "@ema-platform/ui";
 import type { Translations } from "./en";
 
 export const am: Translations = {
+  landing: landingAm,
+
   app: {
     name: "ኢማ አስተዳደር",
     shortName: "ኢማ",

apps/backoffice/src/app/i18n/locales/en.ts

@@ -1,4 +1,8 @@
+import { landingEn } from '@ema-platform/ui';
+
 export const en = {
+  landing: landingEn,
+
   app: {
     name: 'EMA Admin',
     shortName: 'EMA',