feat(i18n): move language switcher into footer, restyle laconic

- remove {{> lang-switch}} from header-home/case/minimal
- add {{> lang-switch}} to footer
- restyle .lang-switch as compact text group 'RU / EN' (active = accent),
  drop pill borders/background for a minimal look

src/partials/footer.html

@@ -3,5 +3,6 @@
         <span class="footer__chunk footer__chunk--date">© 2015–2026<span class="footer__sep" aria-hidden="true"> · </span></span>
         <span class="footer__chunk footer__chunk--main">{{i18n:footer.credit}}</span>
         <span class="footer__chunk footer__chunk--meta footer__attr"><span class="footer__sep" aria-hidden="true"> · </span><a href="{{pagePrefix}}cases/design-system/">{{i18n:footer.designSystem}}</a><span class="footer__sep" aria-hidden="true"> · </span><a href="{{pagePrefix}}cookie-policy/">{{i18n:footer.cookiePolicy}}</a></span>
+        <span class="footer__chunk footer__chunk--lang"><span class="footer__sep" aria-hidden="true"> · </span>{{> lang-switch}}</span>
       </div>
     </footer>

src/partials/header-case.html

@@ -6,7 +6,6 @@
           <nav class="nav" aria-label="{{i18n:nav.aria}}">
             <a href="#contact">{{i18n:nav.contact}}</a>
           </nav>
-          {{> lang-switch}}
         </div>
       </div>
     </header>

src/partials/header-home.html

@@ -20,7 +20,6 @@
             </button>
             <div id="nav-more-menu-dock" class="nav-more__dock" hidden data-nav-more-menu></div>
           </div>
-          {{> lang-switch}}
         </div>
       </div>
     </header>

src/partials/header-minimal.html

@@ -7,7 +7,6 @@
           <nav class="nav" aria-label="{{i18n:nav.aria}}">
             <a href="{{pagePrefix}}">{{i18n:back.home}}</a>
           </nav>
-          {{> lang-switch}}
         </div>
       </div>
     </header>