rss_guard marked the victim slot eid=-1 under the lock, unlocked, and only then
freed s->slab. In that window the slot reads as {eid=-1, slab still valid} --
exactly the state pilot_realload's victim scan reuses first -- so a pilot worker
could claim it and pread into the slab while it was being freed: use-after-free,
or a double-free if the loader took its own realloc path.
Keep the free and the pointer/capacity NULLing inside the critical section, so
'slab valid' and 'slot reusable' are never simultaneously observable. The lock is
held across a free() (microseconds); workers only take it briefly for scan+reserve.
Reproduces on dev with a SINGLE pilot worker (rss_guard runs on the main thread
while the pilot worker runs in the background), whenever the RAM guard is active
(RSS_GUARD_GB, or any resolved g_ram_budget_gb).
make check 83/83, native + portable builds 0 warnings.
cdhdt
9c5ab39b62