v1.6.0 — Automatic Provider Fallback

v1.6.0\n\n### Added\n- Automatic provider fallback: when an LLM provider fails (rate limit, timeout, etc.), �[32m[bl]�[0m# automatically tries the next configured provider in order\n- Auto-save working provider: if a different provider succeeds, it's saved as the new default in for future queries\n- User-visible message: (auto-switched to "provider-name" for future queries)\n\n### Behavior\n- Config errors (missing provider, bad config) still exit immediately — only API errors trigger fallback\n- Interactive mode uses primary provider (fallback not supported in REPL)\n- CLI flags --llm-provider / --llm-model / --llm-key only apply to the initially requested provider