Add Redux and reducers.

Load i18n files and add dayjs.

src/redux/reducers/auth.ts

@@ -0,0 +1,48 @@
+import { Auth } from "revolt.js/dist/api/objects";
+
+export interface AuthState {
+    accounts: {
+        [key: string]: {
+            session: Auth.Session;
+        };
+    };
+    active?: string;
+}
+
+export type AuthAction =
+    | { type: undefined }
+    | {
+          type: "LOGIN";
+          session: Auth.Session;
+      }
+    | {
+          type: "LOGOUT";
+          user_id?: string;
+      };
+
+export function auth(
+    state = { accounts: {} } as AuthState,
+    action: AuthAction
+): AuthState {
+    switch (action.type) {
+        case "LOGIN":
+            return {
+                accounts: {
+                    ...state.accounts,
+                    [action.session.user_id]: {
+                        session: action.session
+                    }
+                },
+                active: action.session.user_id
+            };
+        case "LOGOUT":
+            const accounts = Object.assign({}, state.accounts);
+            action.user_id && delete accounts[action.user_id];
+
+            return {
+                accounts
+            };
+        default:
+            return state;
+    }
+}