docs: add rdplot paper review (CCT 2015 JASA)

PR-A of the rdplot diagnostic arc (2-PR methodology structure). Adds the
methodology review of Calonico, Cattaneo & Titiunik (2015), "Optimal
Data-Driven Regression Discontinuity Plots" (JASA 110(512):1753-1769) and
its supplemental appendix: ES/QS partition schemes, Theorem 1-2
variance/bias constants, all IMSE-optimal / WIMSE / mimicking-variance
bin selectors (Eq 1-6) with the implied-weights inverse map (Supplement
S.1), the spacings and series data-driven implementations (Eq 7-26,
Supplement SA-1..SA-20, Lemma SA3), edge cases, and transcribed smoke
targets for the Lee House, Senate, Progresa, and Head Start applications.
Also lists the new review in the RD "Paper reviews on file" REGISTRY
index. Implementation (rdplot port + parity + docs wiring) is the
follow-up PR-B.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VwhFMnFQGBumYfwbeQaUjm

Author: igerber

docs/methodology/REGISTRY.md

@@ -3946,6 +3946,8 @@ CI-shrinkage anchors).
 **Paper reviews on file:**
 `docs/methodology/papers/calonico-cattaneo-titiunik-2014-review.md` (CCT 2014,
 Econometrica - robust bias-corrected RD inference),
+`calonico-cattaneo-titiunik-2015-review.md` (JASA - optimal data-driven RD
+plots; bin-count selector formulas for the planned rdplot diagnostic),
 `calonico-cattaneo-farrell-titiunik-2017-review.md` (Stata Journal - the
 rdrobust software reference this port parity-targets),
 `calonico-cattaneo-farrell-2018-review.md` (JASA - CER-optimal bandwidths),