0.11b regression checklist
==========================

1. Build both EXE and shell DLL with FASM 1.73.35.
2. Encrypt/decrypt small files: behavior and final bytes unchanged.
3. Encrypt/decrypt a large file on a slower SSD. At ~70%: + Sync should pulse
   smoothly and Windows should not show "Keine Rückmeldung".
4. When the flush completes, + Sync becomes steady black and the On-Disk
   verification line becomes black as phase 2 begins.
5. Cancel during the flush: the UI remains responsive; the flush is joined
   before cleanup and no final output is committed.
6. Explorer context menu and .$#! icon registration remain as in 0.11a.
7. CT64FILE v1 test vector and all prior boundary tests remain unchanged.
