feat(aphoria): implement claims architecture (A1-A5) with verify engine, corpus, coverage, and explain
Complete Aphoria claims system overhaul:
- A1: Rename ExtractedClaim to Observation (extractors produce observations, not claims)
- A2: Add AuthoredClaim with full provenance, invariants, and authority tiers
- A3: Verify engine comparing observations against authored claims, CLI + formatters
- A4: Corpus as first-class assertions with predicate indexing, authority lens, trust packs
- A5: Coverage analysis, explain/docs generation, self-audit extractor, claim suggester skill
Also includes: 42 extractors updated for Observation type, verifiable_predicates trait,
conflict detection with comparison modes, claims TOML persistence, Grafana dashboard,
backup/restore scripts, and comprehensive test coverage.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>