- Add addClamped() in new header clamped_arithmetic.h; uses a 64-bit
intermediate so the addition cannot overflow int.
- Use it in Server_Card::incrementCounter() (clamps [0, MAX_COUNTERS_ON_CARD])
and Server_Counter::incrementCount() (clamps [INT_MIN, INT_MAX]), removing
the duplicated overflow-safe logic and its keep-in-sync TODO.
- Inline incrementCount() into server_counter.h; server_counter.cpp now holds
only the constructor and getInfo().
- Clarify the card-counter bounds comment in trice_limits.h.
