v0.5.7-ttl-fix
Changes:
- Active webchat chats no longer 401 after ~30 min: each accepted activity/reconnect extends an in-memory per-conversation sliding window and re-mints a fresh full-life JWT (swapped upstream, echoed as _directline.renewed_token); idle chats still expire.
- Added local POST /v3/directline/tokens/refresh (fresh-TTL, same conversationId), GREENTIC_DIRECTLINE_TOKEN_TTL_SECS knob (60–604800 s, default 1800), and code on auth errors (TokenExpired/InvalidToken/WrongConversation) + Link to refresh.