Public-release polish: self-contained ST embedder (no internal deps),…

… requirements, CITATION.cff, honest technical report (paper/), README install update

Routing/abstention now reproduce with pip-only sentence-transformers (AURC 0.004 verified). Additive only; caveats and the retracted 0.675 result preserved.

Public-release polish: self-contained ST embedder (no internal deps),…

… requirements, CITATION.cff, honest technical report (paper/), README install update

Routing/abstention now reproduce with pip-only sentence-transformers (AURC 0.004 verified). Additive only; caveats and the retracted 0.675 result preserved.