Synthadoc: Staleness Detection, Full Audit Trails, and Four Export Formats - No Extra LLM Calls

Synthadoc v0.6.0 adds a five-state page lifecycle to track freshness and flag stale content more clearly.

Every page transition is now recorded in a permanent audit trail, improving visibility into how knowledge changes over time.

The release also adds wiki exports in four machine-readable formats, preserving content, provenance, history, and cost.

These updates help reduce hidden misinformation in knowledge bases without requiring extra LLM calls.