feat: content classification — domain routing + sub-tags for sources
All source creation functions now classify content by domain and
sub-topic instead of hardcoding internet-finance.
Domain routing: keyword matching (2+ hits) routes to ai-alignment,
health, space-development, entertainment. Default: internet-finance.
Sub-tags for internet-finance: futarchy, ownership-coins, defi,
governance, market-analysis, crypto-infra. Added to source frontmatter
tags array for granular filtering.
Applied to: standalone sources, inline SOURCE:/CLAIM:, conversation
archives, research archives.
Pentagon-Agent: Epimetheus <3D35839A-7722-4740-B93D-51157F7D5E70>