PERF.70 Server: operations checks: two cron jobs without a lock, status-check's serial probes, no Apache scoreboard, static files gzipped per request

bin/mail-poll.php (IMAP, every 5 min) and bin/a Discord member-sandbox-sync.php (every 10 min) have no flock while every other job has one; status-check runs 7 probes serially with 12 to 40 s timeouts plus 5 s retry sleeps (about 2 min worst case inside a 5-min slot; MeCentral timed out once on 2026-11-07). mod_status is on (Require local) but /server-status is rewritten to the 404 page by the catch-all .htaccess, so there is no scoreboard for bin/admin-perf.php --http or future measuring. Static JS is gzipped on every request: cadcraft.js 198 to 59.5 KB costs 9.0 ms p50 against 0.7 ms for an uncompressed file through the same .htaccess, 147 req/s at c=10 and p99 1,029 ms at c=20 (PERF.16 carries the fix: pre-compressed .br/.gz siblings and an immutable one-year cache). Changes: add the flock, run the probes with curl_multi or cap the total at 60 s, a <Location /server-status> with RewriteEngine Off in this site's vhost. Load floors for the record (c=10, keep-alive, zero failures): health 775 req/s, catalog 303, /status 189, / 80, /apps/cadcraft 58, /use/cadcraft 17.4 req/s at p50 586 ms (its 830 KB page is the throughput ceiling: PERF.2, PERF.3).