feat(matlab): add Satterthwaite DF + honest random-slope test to LME reports

Every fitlme-based report (lme_*, paper_*, phase_*, and the variations'
analyze.m) now shows, per effect: residual-DF p, Satterthwaite-DF p, and --
for the interaction -- an HONEST test from a per-animal random-SLOPE model
(day|rat), whose Satterthwaite DF collapses toward the animal count.

New: tdcs_random_slope_interaction.m (shared helper). Wired into tdcs_lme,
tdcs_paper_lme, tdcs_phase_lme, variation_analyze; SUMMARY.csv gains
interaction_p_satt / interaction_p_rs. Regenerated all results/, variations/,
matched-effort outputs.

Key point this surfaces: Satterthwaite ~= residual on the random-INTERCEPT
model (the slope's error is at session level), so it does NOT fix
pseudoreplication; the random-slope model does. Effect: full-range mergeA2
interaction 0.009 -> 0.75 (collapses); unmerge_d0_5 0.015 -> 0.13 (n.s.);
the pooled-control early windows survive honestly (naive_a2_d0_5 0.001 ->
0.028; naive_boxa_d0_5 0.003 -> 0.036). Suite 42/42.

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

analysis/matlab/make_variations.m

@@ -74,7 +74,8 @@ for gi = 1:size(groupings, 1)
         try
             r = localRun(fullfile(folder, 'analyze.m'));
             rows(end + 1, :) = {vname, gname, wname, r.nRats, r.nObs, ...
-                r.covEqual, r.interP, r.interEst, r.stimP, r.dayP}; %#ok<AGROW>
+                r.covEqual, r.interP, r.interPsatt, r.interPrs, r.interEst, ...
+                r.stimP, r.dayP}; %#ok<AGROW>
             fprintf('  %-16s N=%2d obs=%4d  interaction p=%.4g (%+.2f)  %s\n', ...
                 vname, r.nRats, r.nObs, r.interP, r.interEst, ...
                 localTern(r.covEqual, 'equal-cov', 'UNEQUAL-cov'));
@@ -87,8 +88,8 @@ end
 
 % Top-level index of all variations.
 S = cell2table(rows, 'VariableNames', {'variation', 'grouping', 'window', ...
-    'nRats', 'nObs', 'covEqual', 'interaction_p', 'interaction_est', ...
-    'stim_p', 'day_p'});
+    'nRats', 'nObs', 'covEqual', 'interaction_p', 'interaction_p_satt', ...
+    'interaction_p_rs', 'interaction_est', 'stim_p', 'day_p'});
 writetable(S, fullfile(root, 'SUMMARY.csv'));
 fprintf('\nWrote %d variations under %s\n(index: variations/SUMMARY.csv)\n', ...
     size(rows, 1), root);