feat(matlab): verbatim paper LME (behavior ~ stim+day+stim:day+(1|rat)) + power sim on it

Adds tdcs_paper_lme replicating the paper's exact formula/variable names (paper_*
switch cases): mergeA2 reproduces the interaction F(1)=7.09 vs 7.12, p=0.009 vs
0.008, with a coverage-confound warning. Rewrites tdcs_power_sim to fit that same
formula (interaction term canonicalized to day:stim). Adds a replication test.
Suite 37/37.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

analysis/matlab/tdcs_glm.m

@@ -107,6 +107,16 @@ switch scenario
     case 'phase_mergeB2'
         tdcs_phase_lme('mergeB2', cfg);
 
+    % --- Paper replication: behavior ~ stim + day + stim:day + (1|rat) ---
+    case 'paper_unmerged'
+        tdcs_paper_lme('unmerged', cfg);
+
+    case 'paper_mergeA2'
+        tdcs_paper_lme('mergeA2', cfg);
+
+    case 'paper_mergeB2'
+        tdcs_paper_lme('mergeB2', cfg);
+
     otherwise
         error('tdcs_glm:badScenario', ...
             ['Unrecognized scenario "%s". Valid scenarios are: ' ...