feat(auth): add changePassword() to frontend AuthService

APP/src/app/shared/services/auth.service.ts

@@ -147,6 +147,20 @@ export class AuthService {
         return this.refreshInFlight$;
     }
 
+    /**
+     * Changes the current user's password. Sends the cookie so the server can
+     * keep the current session alive while revoking the user's other sessions.
+     * Emits void on success (204); errors propagate so the caller can show the
+     * server message.
+     */
+    changePassword(currentPassword: string, newPassword: string): Observable<void> {
+        return this.http.post<void>(
+            `${this.apiConfig.authUrl}/change-password`,
+            { currentPassword, newPassword },
+            { withCredentials: true }
+        );
+    }
+
     /**
      * Clears in-memory auth state immediately, then fires a fire-and-forget
      * POST to revoke the server-side refresh token cookie.