marketintelhadp/nascdi-apple-price-transmission: v1.2 — NASCDI rebuild + corrected Wald tests

Rebuilds the disruption index on the GDELT-lexicon methodology (src/nascdi/build_nascdi_final.py, config/lexicon_news.yaml), adds the corrected Wald asymmetry test (src/models/nardl/corrected_wald_test.py, results/nardl/tables/wald_asymmetry_tests_fixed.csv), and adds a lexicon sensitivity analysis (config/lexicon_sensitivity.yaml, src/nascdi/build_nacdi_sesitivity.py). Supersedes v1.1, which predates this rebuild.