Improve AI translation: skip Swedish/English, /trans toggle, better prompt

- All messages sent to LLM (not just non-Latin)
- LLM detects language and returns SKIP for understood languages
- /trans toggles echoing translations publicly to channel
- PM nicks ordered most-recent-first for tab completion
- tool_choice:none to fix vLLM/litellm 400 error
- Updated README with /trans command

README.md

@@ -68,6 +68,7 @@ Port defaults to 6667.
 | `/names [#channel]` | List users in channel |
 | `/whois <nick>` | WHOIS query |
 | `/wii <nick>` | Extended WHOIS (queries remote server) |
+| `/trans` | Toggle public translation echo on/off |
 | `/quit [reason]` | Quit (default: "See you later") |
 | `/raw <line>` | Send raw IRC command |