AskChat

Adds persistent memory.

• New save_memory agent tool: Notch can permanently save a short note, shared by every player and persisted across restarts in plugins/AiChatBuddy/memory.txt.
• Used when a player explicitly asks Notch to remember/save/note something, or right after web_search/minecraft_wiki shows Notch was wrong or out of date (e.g. a game update he didn't know about) — so he knows to check next time instead of trusting stale knowledge.
• Saved notes are injected into the system prompt on every question.
• New admin command: /aichat memory <list|forget <index>|clear> (permission aichatbuddy.memory, default op).
• New config section: memory.enabled / memory.max-entries (default 50, oldest notes dropped first).