Fix "failed to parse numa bitmap" on systems with more than 512 CPUs

[wallezhang]

Summary

• Increase CPUMASK_SZ from (64 * 8) (512) to (64 * 64) (4096) to match MAXCPU in photosyst.h
• On systems with more than 512 CPUs, numa_parse_bitmap_v2() exceeded the bitmask array bounds and returned -1, causing a fatal "failed to parse numa bitmap" error

Root Cause

CPUMASK_SZ was hardcoded to 512 bits, but /sys/devices/system/node/nodeX/cpumap on a 768-CPU system contains 768 bits (24 x 32-bit hex groups). The parser merges adjacent 32-bit groups into 64-bit longs, requiring 12 longs, but the array only held 8 (CPU_LONGS(512)). This caused the bounds check if (i >= CPU_LONGS(ncpus)) to fail.

Test plan

• Verified with unit test using actual 768-CPU cpumap data from a production system
• Confirmed the old value (512) reproduces the failure
• Confirmed the new value (4096) parses correctly and produces correct bitmask values
• Verified backward compatibility with smaller systems (64, 128, 512 CPUs)

Fixes #372