AtUnique method
Allocates (or reuses) a slot identified by a unique key suffix.
Behaves like At, but prepends a monotonic ID from RaylibTempBase.nextId to
key, ensuring the slot is never accidentally shared with an unrelated
call that happens to use the same base key.
Useful when the same allocation site may be called multiple times within a single scope and each call must get its own independent buffer.
Implementation
P AtUnique(String key, [int count = 1]) => At(uniqueSlotKey(key), count);