v2.1.6 - Added ZUPT GUI + VaptVupt v2.40

[2.1.6] — 2026-04-22

New zupt info <archive> subcommand: Shows archive metadata without needing a password. Displays format version, UUID, creation timestamp, file size, block count, and all flags (encrypted, PQ hybrid, solid, multithreaded, dedup, disk image). Useful for inspecting archives before decryption, triaging backups, and scripting.
Works on all archive types: plain, encrypted, PQ, dedup, disk images.
Rejects non-archive files with a clear error message.

Weak password detection during zupt compress -p: warns if password is shorter than 8 characters ("very short") or shorter than 12 characters with fewer than 3 character classes ("weak"). Uses character class analysis: uppercase, lowercase, digits, special characters.
Non-blocking: warning is informational only, compression proceeds. PBKDF2 with 600K iterations provides baseline protection even for weaker passwords.

Archive listing header now displays | Dedup, | PQ, | Disk flags when present, making it immediately visible what features an archive uses.

VaptVupt 2.40.0 integrated (production hardening release). 55-case adversarial test suite, 10,200-case differential fuzzer, new vv_xxh64.c and vv_platform.h.
format_v2 enabled: 4-7% better compression ratio on binary data (ELF, shared libraries). All v2.33.0+ decoders read v2 frames transparently.
VV_DECOMPRESS_SKIP_CHECKSUM: Decode skips redundant XXH64 verification since zupt's HMAC-SHA256 already authenticates compressed data. Up to 3.7x faster decode on post-encryption random data.

Cross-platform graphical interface in gui/ subdirectory. Covers all zupt operations: key generation (generate + export public key), compress (all codecs, levels, dedup, solid, password, PQ), extract, verify, info, disk backup/restore.
System integration: Nemo right-click actions (Compress/Extract with Zupt), .zupt MIME type, desktop file.
Packaging: .deb, .rpm, .whl, source tarball, NSIS Windows installer, AppImage, Flatpak configs.
Dynamic version display from zupt binary (no hardcoded version strings). Window icon on all platforms.

97 total: 84 existing (70 core + 8 disk + 6 dedup) + 13 v2.1.6 (7 info, 4 password, 2 list flags). VV unit tests 11/11. ASAN clean.