analysis(matlab): per-variation subfolders (grouping x window) for the paper LME

Add make_variations.m + variation_analyze.m generating 20 self-contained
subfolders under analysis/matlab/variations/, one per grouping x day-window,
each with exactly three files: data.csv (curated subset), analyze.m (a simple
standalone script fitting behavior ~ stim + day + stim:day + (1|rat) on the
success COUNT), and result.txt (its output). Plus variations/SUMMARY.csv.

Groupings (stim=1 / stim=0, other groups dropped):
  unmerge     B2 vs A2
  right_only  B2+Right vs A2            (Box-A dropped)
  naive_a2    B2 vs A2+Naive           (Right, Box-A dropped)
  naive_boxa  B2 vs A2+Naive+Box-A     (Right dropped)
Windows: 0-10, 0-13, 0-5, 6-10, 6-13. All 20 have equal day coverage.

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

analysis/matlab/variations/right_only_d0_10/data.csv

@@ -0,0 +1,73 @@
+subject,group,day,success,total,stim
+Banh-mi-1,Electrode-Box-B2,0,13,84,1
+Banh-mi-1,Electrode-Box-B2,1,35,86,1
+Banh-mi-1,Electrode-Box-B2,2,47,110,1
+Banh-mi-1,Electrode-Box-B2,3,65,140,1
+Banh-mi-1,Electrode-Box-B2,4,70,127,1
+Banh-mi-1,Electrode-Box-B2,5,102,142,1
+Banh-mi-1,Electrode-Box-B2,6,90,131,1
+Banh-mi-1,Electrode-Box-B2,7,109,148,1
+Banh-mi-1,Electrode-Box-B2,8,104,137,1
+Banh-mi-1,Electrode-Box-B2,9,119,150,1
+Banh-mi-1,Electrode-Box-B2,10,121,158,1
+Banh-mi-2,Electrode-Box-A2,0,25,97,0
+Banh-mi-2,Electrode-Box-A2,1,22,101,0
+Banh-mi-2,Electrode-Box-A2,2,22,119,0
+Banh-mi-2,Electrode-Box-A2,3,29,118,0
+Banh-mi-2,Electrode-Box-A2,4,27,136,0
+Banh-mi-2,Electrode-Box-A2,5,43,146,0
+Banh-mi-2,Electrode-Box-A2,6,74,146,0
+Banh-mi-2,Electrode-Box-A2,7,70,148,0
+Banh-mi-2,Electrode-Box-A2,8,65,130,0
+Banh-mi-2,Electrode-Box-A2,9,79,151,0
+Banh-mi-2,Electrode-Box-A2,10,93,152,0
+Egg-tart-1,Electrode-Box-B2,0,7,56,1
+Egg-tart-1,Electrode-Box-B2,1,16,78,1
+Egg-tart-1,Electrode-Box-B2,2,23,103,1
+Egg-tart-1,Electrode-Box-B2,3,63,120,1
+Egg-tart-1,Electrode-Box-B2,4,69,132,1
+Egg-tart-1,Electrode-Box-B2,5,83,136,1
+Egg-tart-1,Electrode-Box-B2,6,71,142,1
+Egg-tart-1,Electrode-Box-B2,7,79,138,1
+Egg-tart-1,Electrode-Box-B2,8,98,142,1
+Egg-tart-1,Electrode-Box-B2,9,89,139,1
+Egg-tart-1,Electrode-Box-B2,10,96,143,1
+Egg-tart-2,Electrode-Box-A2,0,9,32,0
+Egg-tart-2,Electrode-Box-A2,1,2,38,0
+Egg-tart-2,Electrode-Box-A2,2,31,93,0
+Egg-tart-2,Electrode-Box-A2,3,44,101,0
+Egg-tart-2,Electrode-Box-A2,4,54,131,0
+Egg-tart-2,Electrode-Box-A2,5,84,139,0
+Egg-tart-2,Electrode-Box-A2,6,85,145,0
+Egg-tart-2,Electrode-Box-A2,7,79,143,0
+Egg-tart-2,Electrode-Box-A2,8,76,131,0
+Egg-tart-2,Electrode-Box-A2,9,88,149,0
+Egg-tart-2,Electrode-Box-A2,10,81,151,0
+Khoai-lang-1,Right-Electrode,0,3,69,1
+Khoai-lang-1,Right-Electrode,1,18,97,1
+Khoai-lang-1,Right-Electrode,2,27,84,1
+Khoai-lang-1,Right-Electrode,3,46,121,1
+Khoai-lang-1,Right-Electrode,4,65,143,1
+Khoai-lang-1,Right-Electrode,5,76,141,1
+Khoai-lang-1,Right-Electrode,6,79,146,1
+Khoai-lang-1,Right-Electrode,7,81,153,1
+Khoai-lang-1,Right-Electrode,8,98,144,1
+Khoai-lang-1,Right-Electrode,9,101,149,1
+Khoai-lang-1,Right-Electrode,10,103,150,1
+Root-beer-1,Electrode-Box-B2,0,11,85,1
+Root-beer-1,Electrode-Box-B2,1,18,76,1
+Root-beer-1,Electrode-Box-B2,2,40,105,1
+Root-beer-1,Electrode-Box-B2,3,55,134,1
+Root-beer-1,Electrode-Box-B2,4,75,136,1
+Root-beer-1,Electrode-Box-B2,5,64,133,1
+Root-beer-1,Electrode-Box-B2,6,104,139,1
+Root-beer-1,Electrode-Box-B2,7,98,148,1
+Root-beer-1,Electrode-Box-B2,8,81,145,1
+Root-beer-1,Electrode-Box-B2,9,89,156,1
+Root-beer-1,Electrode-Box-B2,10,105,158,1
+Root-beer-2,Electrode-Box-A2,0,22,74,0
+Root-beer-2,Electrode-Box-A2,1,31,87,0
+Root-beer-2,Electrode-Box-A2,2,49,134,0
+Root-beer-2,Electrode-Box-A2,3,31,89,0
+Root-beer-2,Electrode-Box-A2,4,60,140,0
+Root-beer-2,Electrode-Box-A2,5,84,147,0