Value method
Returns a P for text using the next anonymous ring-buffer slot.
Anonymous slots cycle modulo slotCount, so older anonymous strings may be overwritten.
If key is provided, delegates to ValueAt instead.
Implementation
P Value(String text, [String? key]) {
if (key != null) return ValueAt(key, text);
final slot = stringAnonIndex;
stringAnonIndex = (stringAnonIndex + 1) % slotCount;
_ensureSlotExists(slot);
return writeToSlot(slot, text);
}