log.ts stderr and sink boundaries

Errors and actionable notice() warnings remain stderr-visible without LORE_DEBUG; embedded/TUI suppression may hide stderr but never persistent logs or registered LogSinks. Only LORE_DEBUG=1 or case-insensitive true enables debug output—nonempty 0/false must not. Pass the actual Error to error() for sanitized capture. Logging, sinks, tracing, rotation, and formatting are best-effort and must never alter behavior; host logger failures must not interrupt worker-stream draining.