feat(auth): revoke all sessions on password reset

After updating the user password during a reset flow, calls
authService.revokeAllSessions(email) to invalidate every active session
for the account — prevents an attacker with a stolen session from
retaining access after the owner resets their password.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/main/java/org/raddatz/familienarchiv/user/PasswordResetService.java

@@ -5,6 +5,7 @@ import java.time.LocalDateTime;
 import java.util.HexFormat;
 import java.util.Optional;
 
+import org.raddatz.familienarchiv.auth.AuthService;
 import org.raddatz.familienarchiv.user.ResetPasswordRequest;
 import org.raddatz.familienarchiv.exception.DomainException;
 import org.raddatz.familienarchiv.exception.ErrorCode;
@@ -32,6 +33,7 @@ public class PasswordResetService {
     private final UserService userService;
     private final PasswordResetTokenRepository tokenRepository;
     private final PasswordEncoder passwordEncoder;
+    private final AuthService authService;
 
     @Autowired(required = false)
     private JavaMailSender mailSender;
@@ -85,6 +87,8 @@ public class PasswordResetService {
 
         resetToken.setUsed(true);
         tokenRepository.save(resetToken);
+
+        authService.revokeAllSessions(user.getEmail());
     }
 
     /**