feat: Multiple LLMs support via ollama, and misc fixes

[dimaosipa]

Multiple LLMs support:

• adds ability to provide pretty much any model as long as it is compatible with OpenAI API, including llama models via Ollama
• adds ability to use different model providers for different agents (for example local llama for curriculum_qa, skill_manager)
• switches default models to gpt-4.1-nano. However gpt-4 seems to perform better overall
• updates readme

Misc fixes:

• freezes python dependencies, so next time someone downloads the project, they use correct versions of all the tools
• migrates to latest Langchain
• fixes typescript build of mineflayer-collectblock
• fixes plugin imports in mineflayer
• some fixes around how mineflayer server restarts, adds timeout to improve probability that the desired port is no longer in use
• adds ability to send messages to bot via API, however bot does seem to ignore those