fix(ui): proper OIDC logout — server revoke + top-level redirect

Previous logout fired fetch(end_session, {mode:'no-cors'}), which is a
no-op for OIDC: cross-origin fetch never clears the IdP's session cookie.
Result: subsequent SSO clicks silently re-authenticated the prior user.

New flow:
1. Best-effort POST /auth/logout to bump token_revoked_before.
2. Clear localStorage + Zustand state.
3. Set sessionStorage 'cameleer:signed_out=1' so /login renders a
   confirmation splash (mirrors cameleer-saas pattern).
4. window.location.replace(end_session_endpoint?id_token_hint=...
   &post_logout_redirect_uri=...&client_id=...) — top-level navigation,
   the only form that actually clears the IdP session cookie.

client_id is now persisted at OIDC initiation alongside
end_session_endpoint and id_token, so logout has all three params
without an extra round-trip.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ui/src/auth/LoginPage.tsx

@@ -77,6 +77,9 @@ export function LoginPage() {
       if (data.endSessionEndpoint) {
         localStorage.setItem('cameleer-oidc-end-session', data.endSessionEndpoint);
       }
+      if (data.clientId) {
+        localStorage.setItem('cameleer-oidc-client-id', data.clientId);
+      }
       const redirectUri = `${window.location.origin}${config.basePath}oidc/callback`;
       const scopes = ['openid', 'email', 'profile', ...PLATFORM_SCOPES, ...(data.additionalScopes || [])];
       const params = new URLSearchParams({

ui/src/auth/auth-store.ts

@@ -13,7 +13,7 @@ interface AuthState {
   login: (username: string, password: string) => Promise<void>;
   loginWithOidcCode: (code: string, redirectUri: string) => Promise<void>;
   refresh: () => Promise<boolean>;
-  logout: () => void;
+  logout: () => Promise<void>;
 }
 
 function parseRolesFromJwt(token: string): string[] {
@@ -140,12 +140,26 @@ export const useAuthStore = create<AuthState>((set, get) => ({
     }
   },
 
-  logout: () => {
+  logout: async () => {
+    const accessToken = get().accessToken;
     const endSessionEndpoint = localStorage.getItem('cameleer-oidc-end-session');
     const idToken = localStorage.getItem('cameleer-oidc-id-token');
+    const clientId = localStorage.getItem('cameleer-oidc-client-id');
+
+    // Best-effort server-side revocation. Don't fail logout if it errors —
+    // the SPA-side cleanup below is authoritative for the SPA.
+    if (accessToken) {
+      try {
+        await api.POST('/auth/logout', {});
+      } catch {
+        // ignore
+      }
+    }
+
     clearTokens();
     localStorage.removeItem('cameleer-oidc-end-session');
     localStorage.removeItem('cameleer-oidc-id-token');
+    localStorage.removeItem('cameleer-oidc-client-id');
     set({
       accessToken: null,
       refreshToken: null,
@@ -154,17 +168,24 @@ export const useAuthStore = create<AuthState>((set, get) => ({
       isAuthenticated: false,
       error: null,
     });
-    const loginUrl = `${config.basePath}login`;
+
+    // Tell the upcoming /login render that this is a post-logout landing,
+    // not a fresh visit. Mirrors cameleer-saas ui/src/auth/useAuth.ts.
+    sessionStorage.setItem('cameleer:signed_out', '1');
+
+    const localLoginUrl = `${config.basePath}login`;
+
     if (endSessionEndpoint && idToken) {
+      // OIDC RP-Initiated Logout 1.0: top-level navigation, NOT fetch.
+      // Cross-origin fetch never clears the IdP's session cookie.
       const params = new URLSearchParams({
         id_token_hint: idToken,
         post_logout_redirect_uri: `${window.location.origin}${config.basePath}login`,
       });
-      fetch(`${endSessionEndpoint}?${params}`, { mode: 'no-cors' }).finally(() => {
-        window.location.href = loginUrl;
-      });
+      if (clientId) params.set('client_id', clientId);
+      window.location.replace(`${endSessionEndpoint}?${params}`);
     } else {
-      window.location.href = loginUrl;
+      window.location.replace(localLoginUrl);
     }
   },
 }));