feat(max): add MAX messenger package, sandboxed with Firejail

MAX is the Russian state-affiliated messenger; the official Qt6 client is
repacked from download.max.ru with no independent security track record,
so it never runs unsandboxed. /usr/bin/max is a wrapper (not a symlink)
that always launches through `firejail --profile=max`; the .desktop Exec
goes through the same wrapper so there's no launch path that bypasses it.
The profile hides the rest of the home directory behind private ~/.config,
~/.cache and ~/.local/share/max subdirectories, drops capabilities, enables
seccomp, blocks system D-Bus, and blacklists the standalone crashpad_handler
crash-report uploader. Full elimination of first-party telemetry isn't
claimed or possible from the sandbox layer alone — documented in LICENSE.

Also wires up repo-wide bookkeeping now that all three package changes
(telegram-desktop -> telegram rename, vk-messenger, max) are in: README
package count/catalog rows, docs/maintenance.md naming table and directory
count, and tools/package_updates.sh + tools/validate_repo.py package lists.

tools/validate_repo.py

@@ -23,15 +23,17 @@ EXPECTED_PACKAGES = (
     "fisher",
     "github-desktop",
     "happ",
+    "max",
     "netbird",
     "nivora-cli",
     "opencode",
     "parsec",
     "pineconemc",
     "tailscale",
-    "telegram-desktop",
+    "telegram",
     "ventoy",
     "vintner",
+    "vk-messenger",
     "vual",
     "yandex-browser-stable",
 )