#2853 Title: Monitor: add a RAM bandwidth tile (DRAM read/write GB/s)

Description

Title: Monitor: add a RAM bandwidth tile (DRAM read/write GB/s)

Strata's speed on RAM-bound setups (experts in host RAM) is mostly limited by memory bandwidth, but the Monitor tab has no RAM tile. Could you add one showing:
- DRAM read/write bandwidth (GB/s), live
- RAM used / total (GB)

On my laptop (Core Ultra 7, 4x48 GB DDR5 running at 4000 MT/s, RTX PRO 4000 16 GB + RTX 3090 eGPU), removing 2 sticks raised decode from 30 to 35 t/s, so bandwidth is clearly the bottleneck and would be very useful to see next to Decode t/s.

Possible sources: Intel PCM / AMD uProf counters, or HWiNFO shared memory on Windows; /sys perf counters on Linux.