- New src/utils/osLimits.ts: reads RLIMIT_NOFILE (soft/hard, from
/proc/self/limits) and vm.max_map_count at open — once per process,
Linux-only, measurement-only — and warns loudly when either sits below the
pool-scale floors (soft NOFILE < 65536, max_map_count < 262144), with the
exact raise commands. On stock defaults the failure otherwise arrives as
EMFILE or a failed mmap deep inside an index open, long after the cause
stopped being visible. An unreadable limit produces NO warning — no
measurement, no claim — so non-Linux platforms stay silent.
- Exported for ops doors: checkOsLimits() returns the full OsLimitsReport;
floors exported as constants. Wired fire-and-forget in performInit after
storage init; the check can never affect open.
- Unit tests pin the parser (incl. 'unlimited'), the floor thresholds, the
null-never-warns rule, and the off-Linux silent path.
