Introduce Config\SecurityEnv holding envPath/backupPath/lockPath so the
security helper reads its target paths from shared configuration instead of
hardcoded ROOTPATH/WRITEPATH literals. security_helperTest.php now redirects
all three to a unique per-run sandbox under sys_get_temp_dir() and tears it
down in tearDown(), so the suite no longer reads/writes the repository's real
.env and is safe to run in parallel.
No helper signature changes; production callers unaffected.
Addresses CodeRabbit item 7 (issue #4700).
Co-Authored-By: opencode <bot@opencode.ai>
