Sub-type aware preinstall, USB drivers/PPKGs, Lab OpenText

- PreInstall runner reads pc-subtype.txt and matches PCTypes against
  both base type (Standard) and composite key (Standard-Machine).
- UDC scoped to Standard-Machine only. eDNC and MachineNumberACLs
  skip on Standard-Timeclock sub-type.
- Lab added to OpenText PCTypes.
- build-usb.sh copies enrollment/ (PPKGs) and drivers-staging/ (Dell
  driver packs) onto USB for self-contained deployment.
- Playbook deploys PPKGs and drivers from USB to PXE server shares.
- Gitignore enrollment/, drivers-staging/, *.ppkg (large binaries).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -50,3 +50,6 @@ mok-keys/
 # Secrets
 secrets.md
 **/eMxInfo*.txt
+*.ppkg
+enrollment/
+drivers-staging/