v0.59.0

Config auto-healing, find() fulltext fallback

• Auto-heal config providers: Fallback providers (truncate, None) are no longer persisted to keep.toml. On load, if key providers are missing, re-detect better options from the environment. Once a real provider (mlx, ollama, voyage, etc.) succeeds, it gets persisted.
• find() fulltext fallback: find gracefully falls back to fulltext search when no embedding provider is configured, instead of crashing.
• Fix --text → --fulltext in error message.