feat: add internationalization message platform

src/presentation/styles/theme.css

@@ -131,11 +131,13 @@
     margin-inline-start: auto;
   }
 
-  .theme-selector {
+  .theme-selector,
+  .locale-selector {
     display: block;
   }
 
-  .theme-selector .ui-field__label {
+  .theme-selector .ui-field__label,
+  .locale-selector .ui-field__label {
     position: absolute;
     width: 1px;
     height: 1px;
@@ -147,13 +149,18 @@
     border: 0;
   }
 
-  .theme-selector .ui-field__input {
+  .theme-selector .ui-field__input,
+  .locale-selector .ui-field__input {
     min-height: var(--size-control-sm);
     max-width: 8.5rem;
     padding: 0.35rem 2rem 0.35rem 0.65rem;
     cursor: pointer;
   }
 
+  .locale-selector .ui-field__input {
+    max-width: 7rem;
+  }
+
   .app-shell__session-error {
     position: absolute;
     top: calc(100% + 0.25rem);
@@ -1340,6 +1347,10 @@
     display: none;
   }
 
+  .app-shell__session .theme-selector {
+    display: none;
+  }
+
   .app-shell__brand {
     display: none;
   }