feat(auth): OIDC phase 4/5/6 — token refresh, logout revocation, account link

- initMatrix.ts: import the shared Session type; when a session has a refresh
  token + oidc metadata, wire a LotusOidcTokenRefresher via createClient's
  refreshToken + tokenRefreshFunction (reactive 401 refresh). Rust crypto is
  unaffected (still keyed on userId/deviceId).
- client/oidcTokenRefresher.ts: OidcTokenRefresher subclass that persists rotated
  tokens back to the fallback session.
- client/oidcLogout.ts + logoutClient: best-effort revoke access+refresh tokens at
  the issuer's revocation_endpoint on logout (tolerant of failure).
- settings/account/OidcManageAccount.tsx: MSC2965 "Manage account" deep-link,
  shown only when authMetadata is present (OIDC servers); mirrors OtherDevices.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/client/initMatrix.ts

@@ -2,16 +2,11 @@ import { createClient, MatrixClient, IndexedDBStore, IndexedDBCryptoStore } from
 
 import { cryptoCallbacks } from './secretStorageKeys';
 import { clearNavToActivePathStore } from '../app/state/navToActivePath';
-import { removeFallbackSession } from '../app/state/sessions';
+import { getFallbackSession, removeFallbackSession, Session } from '../app/state/sessions';
+import { LotusOidcTokenRefresher } from './oidcTokenRefresher';
+import { revokeOidcTokens } from './oidcLogout';
 import { pushSessionToSW } from '../sw-session';
 
-type Session = {
-  baseUrl: string;
-  accessToken: string;
-  userId: string;
-  deviceId: string;
-};
-
 // Thrown when the local IndexedDB has a higher schema version than this SDK expects.
 // This happens after a downgrade (e.g. matrix-js-sdk was briefly upgraded and then reverted).
 export const IDB_VERSION_CONFLICT = 'IDB_VERSION_CONFLICT';
@@ -25,9 +20,17 @@ export const initClient = async (session: Session): Promise<MatrixClient> => {
 
   const legacyCryptoStore = new IndexedDBCryptoStore(globalThis.indexedDB, 'crypto-store');
 
+  // OIDC/next-gen-auth sessions carry a refresh token; wire automatic refresh
+  // (the client calls this reactively on a 401) and persist rotated tokens.
+  const oidcRefresher =
+    session.refreshToken && session.oidc
+      ? new LotusOidcTokenRefresher(session.oidc, session.deviceId, session.userId, session.baseUrl)
+      : undefined;
+
   const mx = createClient({
     baseUrl: session.baseUrl,
     accessToken: session.accessToken,
+    refreshToken: session.refreshToken,
     userId: session.userId,
     store: indexedDBStore,
     cryptoStore: legacyCryptoStore,
@@ -35,6 +38,9 @@ export const initClient = async (session: Session): Promise<MatrixClient> => {
     timelineSupport: true,
     cryptoCallbacks: cryptoCallbacks as any,
     verificationMethods: ['m.sas.v1'],
+    tokenRefreshFunction: oidcRefresher
+      ? (refreshToken) => oidcRefresher.doRefreshAccessToken(refreshToken)
+      : undefined,
   });
 
   try {
@@ -70,6 +76,11 @@ export const clearCacheAndReload = async (mx: MatrixClient) => {
 export const logoutClient = async (mx: MatrixClient) => {
   pushSessionToSW();
   mx.stopClient();
+  // For OIDC sessions, revoke the tokens at the issuer too (best-effort).
+  const session = getFallbackSession();
+  if (session?.oidc) {
+    await revokeOidcTokens(session);
+  }
   try {
     await mx.logout();
   } catch {