[research] Methodology research doc + per-theme data-source map + formula refinement proposals
- Literature: PEAD (Bernard-Thomas 1990, Fink 2021, Livnat-Mendenhall 2006), EM momentum (lower in EM), multi-criteria EM selection, Thai earnings-surprise thesis
- 5 formula refinements (R1-R5, await user OK): earnings goodwill weight, momentum factor, continuous regime gate, earnings-revision, dividend screen
- Per-theme additional source table (banks NPL reuses reportID 794, utilities EPPO, retail consumer-comfort...) registered via declarative FACTORS