Function compute_mem_cycles 

pub fn compute_mem_cycles(total_pages: u32) -> u8

L/S memory cycle latency tier as a function of accessible page count (cherry-picked from v2 javm/src/lib.rs::compute_mem_cycles):

• ≤ 8 MiB (2048 pages): 25 cycles (L2)
• ≤ 32 MiB (8192 pages): 50 cycles (L3)
• ≤ 256 MiB: 75 cycles (DRAM)

• 256 MiB: 100 cycles (DRAM saturated)