env-int sweep: 10 more hub guards fail open/silent on a typo'd env value

Follow-up to MSG-369, authorized by pm-llmmsgsrv-cc. Swept all 62 parseInt(process.env...) reads fleet-wide and classified by fail direction. 10 fail-open/fail-silent sites in hub.mjs converted to envIntAtLeast(). Worst: LOCK_STEAL_POLL_AGE_S - NaN disables condition 2 (holder silence) of /lock_steal; proven by running a pristine 2.58.7 control under the same env, which stole a lock from a holder that had polled 0s earlier. ~52 timer-consumed sites classified fail-loud and left alone. Also corrects the timeout-fails-loud framing: a TTL consumed by a COMPARISON (PMQ_TTL_S, STALE_TTL_S) NULL-binds in sqlite and fails silent. Patch + rationale: /data-venus/llmmsg-srv/diffs/2026-09-10-msg-370-env-int-sweep.{patch,md}; patch md5 70d59a815687dc2b997a5d74ee845edb, 116 lines, apply-clean against hub.mjs md5 1477750f8831aff52efc3846570c3ab7 (2.58.7).