Locality Representation Unification — SSOT for Escape Classification

Establish single-source-of-truth for escape-scope classification in AIMS by extending the existing ori_arc::Locality ordered lattice with one new variant (ArgEscaping, sitting between FunctionLocal and HeapEscaping), defining the ori_repr::EscapeInfo per-function storage shape that consumes the unified type, replacing the hardcoded ReprPlan::escapes() query body, eliminating the ParamContract::may_escape LEAK:scattered-knowledge, and coordinating the cross-plan text in repr-opt §08, §09, §10, 00-overview.md, and index.md. Thread-sharing stays in RcStrategy::NonAtomic per the existing repr-opt §10 design; owner-rooted regions stay in BorrowSource (the current home for projection-aware tracking). The plan preserves the ordered escape-scope chain that Locality::join, cross-block widening, and canonicalize Rules 4/6/8 depend on.