Migrate all LLM consumers from direct Ollama calls to centralized
mana-llm service with OpenAI-compatible API.
Migrated services:
- matrix-ollama-bot
- telegram-ollama-bot
- chat-backend
- telegram-project-doc-bot
New env vars: MANA_LLM_URL, LLM_MODEL, LLM_TIMEOUT
Replaces: OLLAMA_URL, OLLAMA_MODEL, OLLAMA_TIMEOUT