i18n: add landing page translations (en/ru)

Added/updated translations for:
- howto: step labels
- stats: suppliers desc, countries
- testimonial: quote, author, role
- roles: subtitle, updated benefits
- cta: register, demo buttons
- footer: all countries, offices, products, services, legal

i18n/locales/en/howto.json

@@ -1,6 +1,7 @@
 {
   "howto": {
     "title": "How It Works",
+    "step": "Step",
     "step1": {
       "title": "Find Materials",
       "description": "Select the raw materials you need, specify quantity and delivery location"