Add full shell, replaceable Omics adapter and bilingual interaction

Implement approved specification #32 and tickets #33-#37. Keep host authentication server-verified and pin session interaction language. Compile scoped base selectors for browser compatibility and retain full gutters during CSS pruning.

frontend/src/shell/host/rememberedSession.ts

@@ -0,0 +1,18 @@
+import type { AuthenticatedUser } from "../../api/types";
+
+type Principal = Pick<AuthenticatedUser, "issuer" | "subject">;
+
+function key(user: Principal) {
+  return `thothii:selected-session:${JSON.stringify([window.location.pathname, user.issuer, user.subject])}`;
+}
+
+export function readRememberedSession(user: Principal): string | null {
+  try { return sessionStorage.getItem(key(user)); } catch { return null; }
+}
+
+export function rememberSession(user: Principal, sessionId: string | null): void {
+  try {
+    if (sessionId) sessionStorage.setItem(key(user), sessionId);
+    else sessionStorage.removeItem(key(user));
+  } catch { /* Reload continuity is optional when browser storage is blocked. */ }
+}