feat(matlab): mergeNaive grouping (control=A2+Naive, tDCS=B2+Right) + GLM/power

Adds cfg.mergeNaive and scenario/paper/phase/power support. This pooled grouping
is the closest replication of the paper's full pattern: paper LME interaction
F(1)=7.30, p=0.008 (paper 7.12/0.008), stim main n.s. (p=0.21 = equal on Day 1),
strong day effect; the overall tDCS advantage is significant at the cluster-honest
per-animal level (rate p=0.003) and well powered. Adds a grouping test. Suite 38/38.

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

analysis/matlab/tdcs_glm.m

@@ -60,6 +60,22 @@ switch scenario
         R = tdcs_models(S, meta, cfg);
         tdcs_report(S, R, meta, cfg, 'mergeB2_d0_10');
 
+    % --- mergeNaive: control = Box-A2 + Naive, tDCS = Box-B2 + Right-Electrode ---
+    case 'mergeNaive_full'
+        [S, meta] = tdcs_scenario_data('mergeNaive_full');
+        R = tdcs_models(S, meta, cfg);
+        tdcs_report(S, R, meta, cfg, 'mergeNaive_full');
+
+    case 'mergeNaive_d0_10'
+        [S, meta] = tdcs_scenario_data('mergeNaive_d0_10');
+        R = tdcs_models(S, meta, cfg);
+        tdcs_report(S, R, meta, cfg, 'mergeNaive_d0_10');
+
+    case 'mergeNaive_d0_13'
+        [S, meta] = tdcs_scenario_data('mergeNaive_d0_13');
+        R = tdcs_models(S, meta, cfg);
+        tdcs_report(S, R, meta, cfg, 'mergeNaive_d0_13');
+
     % --- Linear "days x tDCS" mixed model (Box-B2 vs Box-A2), per the paper ---
     case 'lme_unmerged_full'
         L = tdcs_lme(tdcs_scenario_data('unmerged_full'), cfg);
@@ -117,6 +133,12 @@ switch scenario
     case 'paper_mergeB2'
         tdcs_paper_lme('mergeB2', cfg);
 
+    case 'paper_mergeNaive'
+        tdcs_paper_lme('mergeNaive', cfg);
+
+    case 'phase_mergeNaive'
+        tdcs_phase_lme('mergeNaive', cfg);
+
     otherwise
         error('tdcs_glm:badScenario', ...
             ['Unrecognized scenario "%s". Valid scenarios are: ' ...