fix(auth): refresh cached user after self-role edit so RoleSwitcher shows up

extra_roles changes made to the currently-logged-in admin's own account
weren't reflected until logout/login, since AuthContext only fetches
/users/me once at mount. Now refetches it when the edited user is the
caller themselves.

frontend/src/context/AuthContext.tsx

@@ -28,6 +28,10 @@ interface AuthState {
    * Reloads the page afterward so every role-gated component (nav, route
    * guards, etc.) re-evaluates cleanly against the new role. */
   switchRole: (role: string) => Promise<void>;
+  /** Re-fetch the current user from /users/me — call after an admin edits
+   * the logged-in user's own role/extra_roles so gated UI (e.g. the role
+   * switcher) picks it up without requiring a logout/login. */
+  refreshUser: () => Promise<void>;
 }
 
 const AuthContext = createContext<AuthState | undefined>(undefined);
@@ -93,6 +97,7 @@ export function AuthProvider({ children }: { children: ReactNode }) {
         login,
         logout,
         switchRole,
+        refreshUser,
       }}
     >
       {children}