Basic account and session system

Provide a basic account system with login and server side session store
identified by a cookie.  Upon successful login a signed session cookie
is set by the server with the session stored on the server identifying
which account it is logged in as.  The client uses a shared useFetch on
the session endpoint to identify if it's logged in and which account it
is logged in as, and refreshes this when loggin in or out.

shared/types/account.d.ts

@@ -1,4 +1,21 @@
+export interface Account {
+	id: number,
+	type: "anonymous" | "regular" | "crew" | "admin",
+	/** Name of the account. Not present on anonymous accounts */
+	name?: string,
+}
+
 export interface Subscription {
 	type: "push",
 	push: PushSubscriptionJSON,
 }
+
+export interface Session {
+	id: number,
+	accountId: number,
+}
+
+export interface AccountSession {
+	id: number,
+	account: Account,
+}