docs: complete zupt → vaptvupt rename; README v4.0.0 refresh

- README: add 'What's new in 4.0.0' section, extend release history
  v2.2.4 → v4.0.0, fix stale section titles (benchmark/security/feature
  tables), point fast-install at short.securityops.co/vaptvupt, fix
  related-project links (vaptvupt-codec, libvuptsdk, real repo names)
- install.sh: clone the renamed repo, vaptvupt success message
- Rename remaining zupt → vaptvupt across INSTALL.md, DISTRIBUTION.md,
  SECURITY.md, THREAT_MODEL.md, ROADMAP.md, THIRD-PARTY-NOTICES.md,
  gui/ + sdk/ + packaging READMEs, doc/vaptvupt.1, spec comments/URLs
- New doc/vaptvupt-gui.1 (GUI 1.3.0, VAPTVUPT_BIN/ZUPT_BIN env vars);
  doc/zupt-gui.1 kept as hardlinked compat copy
- Deliberately unchanged: .zupt extension, ZUPT header magic,
  ZUPT-* crypto domain-separation constants, zupt_*/ZUPT_* code
  identifiers, libzuptsdk artifact names, legacy symlink notes,
  CHANGELOG/AUDIT historical entries, Provides/Obsoletes upgrade path
- tests/test_packaging_syntax.sh: THREAT_MODEL section titles updated

install.sh

@@ -1,18 +1,18 @@
 #!/usr/bin/env bash
 # SPDX-License-Identifier: AGPL-3.0-or-later
 # Copyright (c) 2025-2026 Cristian Cezar Moisés
-# Fast Installer for Zupt - GNU/Linux
+# Fast Installer for VaptVupt - GNU/Linux
 
 set -e
 
-echo "🔧 Installing Zupt..."
+echo "🔧 Installing VaptVupt..."
 
 # Create temporary directory
 TMP_DIR=$(mktemp -d)
 
 # Clone and build
-git clone https://git.securityops.co/cristiancmoises/zupt.git "$TMP_DIR/zupt"
-cd "$TMP_DIR/zupt"
+git clone https://git.securityops.co/cristiancmoises/vaptvupt.git "$TMP_DIR/vaptvupt"
+cd "$TMP_DIR/vaptvupt"
 
 make clean
 make
@@ -20,8 +20,8 @@ make
 # Install
 sudo make install
 
-echo "✅ Zupt successfully installed to /usr/local/bin/zupt"
-echo "🔒 You can now run: zupt"
+echo "✅ VaptVupt successfully installed to /usr/local/bin/vaptvupt"
+echo "🔒 You can now run: vaptvupt   (legacy 'zupt' symlink also installed)"
 
 # Cleanup
 cd ~