docs(er): add canonical ER.a2ml covering 22 entities and 39 relationships

Walks the full 11-step trust pipeline (integrity → portfolio → certs →
axiom-scan → confidence → mutation → pareto → statistics → dispatch) and
maps every named struct/enum in core.rs + verification/* to an entity
section with PK, fields, source line-refs, and explicit coverage-audit
table.  Includes the four verisim-feature entities (Proof, TacticApplication,
ProofVersion, ProofStateRecord) plus supporting types (DispatchResult,
PortfolioResult, StatisticsTracker).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: hyperpolymath