v0.5.0 — Forward Secrecy, PyNaCl, Ratchet

Cryptography
- Migrated from Fernet/HKDF to PyNaCl XSalsa20-Poly1305 + BLAKE2b
- Sender Keys ratchet (/ratchet start) — per-message unique keys, forward secrecy
- Full mesh fix: initiator now distributes all chain keys to all peers
- Ratchet invite triggers full restart instead of forwarding live chains
- X25519 pairwise DH, Ed25519 identity signing, ChaCha20-Poly1305 file transfer

Architecture
- Refactored into smaller modules: client_ratchet, client_dh, client_send,
  client_recv, client_commands, client_tofu, server_handlers, server_rooms

New features
- /ratchet start — group forward secrecy, all clients confirm
- /ratchet invite — re-add a user with full ratchet restart
- /proceed — vote to continue after peer migration
- Ratchet activation animation (CRT red with gear art + SFX)
- Ratchet deactivation animation (cyan reverse)
- --generate-access-key and --generate-chat-key CLI flags
- Termux: SODIUM_INSTALL=system for fast PyNaCl install

Changes
- /nick removed (no server-side identity validation)
- /clear now actually clears messages
- /join and /leave warn before breaking ratchet session
- Solo ratchet auto-exit when all peers disconnect

v0.4 — modular rewrite (core/, network/, ui/), signed manifest, firew…

…all module, improved TUI, fixed Windows support

v0.3.1 — fix file transfer (receiver, rate limit, UI freeze, TCP)

v0.3.0 — security hardening, notification sounds, KZ animation

- fix: path traversal in file receive
- fix: group chat Ed25519 signatures
- fix: TLS cert mismatch drops connection
- fix: server-side privmsg rate limit 25/15min
- fix: file chunk cap + index validation
- feat: update.py SHA-256 manifest integrity check
- feat: message tags (!ok !warn !danger !info !req !?)
- feat: notification sounds + custom sounds/ folder
- feat: word-by-word cipher wave animation
- feat: 18-category emotion detection engine