PatchLevelManager resolves the active security patch from
PlayIntegrityFix via the same six-path override chain as
Tricky-Addon's get_extra.sh (pif.json/pif.prop/custom.pif.*,
later entries override earlier ones). Falls back to live
ro.build.version.security_patch when no PIF source is present.
updateTo() validates YYYY-MM-DD format, rejects dates below
2020-01-01 or more than one year older than today, then atomically
stages security_patch.txt with explicit system/boot/vendor dates
and resetprops ro.build.version.security_patch plus
ro.vendor.build.security_patch. Cert tags 706/718/719 then encode
consistent dates via AndroidDeviceUtils.parsePatchLevelValue
(YYYYMM for OS, YYYYMMDD for VENDOR/BOOT per AOSP Tag.aidl).
Wired from App.main after BootStateManager.apply().