feat(ui): real friend-invite share with a per-bot link

The friend-code 'share' was an <a> that just opened the bot. Make it a real share:
Telegram's native share-to-chat picker inside the Mini App (openTelegramLink +
t.me/share/url), the system share sheet (navigator.share) on the web, else copy the
link. The shared deep link points at the same bot the player is in — it picks
VITE_TELEGRAM_LINK_EN/_RU by the session's service language, falling back to the
single VITE_TELEGRAM_LINK. Adds the per-bot build args across Dockerfile / compose /
ci.yaml / .env / docs; PLAN TODO-5 updated.

gateway/Dockerfile

@@ -23,12 +23,16 @@ RUN corepack enable && corepack prepare pnpm@11.0.9 --activate
 # VITE_APP_VERSION carries `git describe` for the About screen (defaults to "dev").
 ARG VITE_TELEGRAM_BOT_ID=
 ARG VITE_TELEGRAM_LINK=
+ARG VITE_TELEGRAM_LINK_EN=
+ARG VITE_TELEGRAM_LINK_RU=
 ARG VITE_TELEGRAM_GAME_CHANNEL_NAME_EN=
 ARG VITE_TELEGRAM_GAME_CHANNEL_NAME_RU=
 ARG VITE_GATEWAY_URL=
 ARG VITE_APP_VERSION=
 ENV VITE_TELEGRAM_BOT_ID=$VITE_TELEGRAM_BOT_ID \
     VITE_TELEGRAM_LINK=$VITE_TELEGRAM_LINK \
+    VITE_TELEGRAM_LINK_EN=$VITE_TELEGRAM_LINK_EN \
+    VITE_TELEGRAM_LINK_RU=$VITE_TELEGRAM_LINK_RU \
     VITE_TELEGRAM_GAME_CHANNEL_NAME_EN=$VITE_TELEGRAM_GAME_CHANNEL_NAME_EN \
     VITE_TELEGRAM_GAME_CHANNEL_NAME_RU=$VITE_TELEGRAM_GAME_CHANNEL_NAME_RU \
     VITE_GATEWAY_URL=$VITE_GATEWAY_URL \