https://gitlab.synchro.net/main/sbbs/-/commit/0413292545602068f2591c10
Modified Files:
src/sbbs3/ctrl/MainFormUnit.cpp
Log Message:
sbbsctrl: count total_users() on a background thread, not the GUI thread

TMainForm::StatsTimerTick() called total_users() directly on the VCL message-pump thread. total_users() walks the entire user base, reading
every record (a lock/read/unlock per user); on a large base - especially a network-mounted data_dir - that is slow, and while the servers are busy
(e.g. a web scrape saturating the file share) it froze the GUI for seconds
at a time. 1eb9328327 (limited-19-blackjack) reduced how often the scan
runs, but throttling frequency can't stop an individual O(N) blocking scan
from freezing the UI when it does run.

Run the scan on a short-lived background thread (_beginthread, matching the server-launch threads in this file). The worker never touches the VCL: it publishes the count, and StatsTimerTick() picks it up on a later tick. The existing frequency guard and the !StatsForm->Visible early-return are kept,
so a hidden Stats window still scans nothing and at most one scan runs at a time.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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