Remove the LightEpoch EntryAt accessor - #2033

libs/storage/Tsavorite/cs/src/core/Epochs/LightEpoch.cs:618

• This re-dereferences tableAligned + entry multiple times in a tight path. Consider caching a single ref to the slot (e.g., ref var slot = ref *(tableAligned + entry);) and then using slot.localCurrentEpoch / slot.threadId to reduce repeated address computation and improve readability without reintroducing a helper call frame.

            if ((*(tableAligned + entry)).localCurrentEpoch != 0)
                return false;

            var epoch = Volatile.Read(ref CurrentEpoch);
            if (Interlocked.CompareExchange(ref (*(tableAligned + entry)).localCurrentEpoch, epoch, 0) != 0)
                return false;

            // The slot is now exclusively ours, so threadId needs no interlocked write.
            (*(tableAligned + entry)).threadId = Metadata.threadId;

libs/storage/Tsavorite/cs/src/core/Epochs/LightEpoch.EntryTable.cs:18

• Both assertions reuse the same primary message but provide different detail strings, which can lead to confusing output (and potentially multiple assertion dialogs) when index is invalid. Consider collapsing this into a single assertion with a clearer, specific detail for each failure mode (or early-return after the first failure) so debug failures are more actionable.

        private static void DebugAssertEntryReserved(int index, string message = "No epoch table entry is reserved for this thread")
        {
            Debug.Assert(index != kInvalidIndex, message, "No slot is reserved for this thread.");
            Debug.Assert(index > kInvalidIndex && index <= kTableSize, message, $"Slot {index} is out of range.");
        }