Landing v2: icon switchers, ephemeral theme, channel link, drop browser CTA

Owner review-pass rework of the landing page:
- Rename the per-language Telegram link build var
  VITE_TELEGRAM_LINK_EN/_RU -> VITE_TELEGRAM_GAME_CHANNEL_NAME_EN/_RU
  (it carries a channel username; the landing builds https://t.me/<name> --
  the same channels the connector posts to via TELEGRAM_GAME_CHANNEL_ID_*).
- Language switcher -> a globe icon dropdown (flags + names), saved + synced
  to the app prefs.
- Theme switcher -> a sun/moon icon toggle, ephemeral (follows the system
  scheme, no auto, never persisted) -- galaxy-game style.
- Drop the "Play in browser" CTA (no standalone-web onboarding yet).

Docs: FUNCTIONAL(+ru), PLAN, deploy + ui READMEs.

deploy/.env.example

@@ -25,8 +25,8 @@ GM_BASICAUTH_HASH=                     # required; `caddy hash-password` bcrypt
 # --- UI build args (baked into the gateway image) ---------------------------
 VITE_TELEGRAM_BOT_ID=
 VITE_TELEGRAM_LINK=
-VITE_TELEGRAM_LINK_EN=                 # landing "Play in Telegram" link, English bot
-VITE_TELEGRAM_LINK_RU=                 # landing "Play in Telegram" link, Russian bot
+VITE_TELEGRAM_GAME_CHANNEL_NAME_EN=                 # landing "Play in Telegram" link, English bot
+VITE_TELEGRAM_GAME_CHANNEL_NAME_RU=                 # landing "Play in Telegram" link, Russian bot
 VITE_GATEWAY_URL=
 
 # --- Gateway ----------------------------------------------------------------

deploy/README.md

@@ -84,8 +84,8 @@ connector **fails at boot** if both are empty.
 | `GATEWAY_DEFAULT_SUPPORTED_LANGUAGES` | variable | `en,ru` | Variant-gating set for non-Telegram logins (web/email/guest). |
 | `VITE_TELEGRAM_BOT_ID` | variable | _(empty)_ | UI build-arg: numeric bot id for the web Login Widget. |
 | `VITE_TELEGRAM_LINK` | variable | _(empty)_ | UI build-arg: deep-link base for share-to-Telegram (e.g. `https://t.me/<bot>/<app>`). |
-| `VITE_TELEGRAM_LINK_EN` | variable | _(empty)_ | UI build-arg: the landing "Play in Telegram" link for the **English** bot (e.g. `https://t.me/Scrabble_Game`). |
-| `VITE_TELEGRAM_LINK_RU` | variable | _(empty)_ | UI build-arg: the landing "Play in Telegram" link for the **Russian** bot (e.g. `https://t.me/Erudit_Game`). |
+| `VITE_TELEGRAM_GAME_CHANNEL_NAME_EN` | variable | _(empty)_ | UI build-arg: the landing "Play in Telegram" link for the **English** bot (e.g. `https://t.me/Scrabble_Game`). |
+| `VITE_TELEGRAM_GAME_CHANNEL_NAME_RU` | variable | _(empty)_ | UI build-arg: the landing "Play in Telegram" link for the **Russian** bot (e.g. `https://t.me/Erudit_Game`). |
 | `VITE_GATEWAY_URL` | variable | _(empty)_ | UI build-arg: gateway origin; empty = same-origin (the usual single-origin deploy). |
 
 The five `VITE_*` are **build-args** baked into the gateway image at build time, so

deploy/docker-compose.yml

@@ -78,8 +78,8 @@ services:
       args:
         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:-}
         VITE_APP_VERSION: ${APP_VERSION:-dev}
     restart: unless-stopped