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>

BACKUP.md

@@ -0,0 +1,75 @@
+# Experiments Database — Backup
+
+## Location
+```
+/home/sam/synology/Backups/Experiments-DB-Backup/
+├── daily/          ← up to 5 change-triggered daily backups
+├── weekly/         ← up to 2 unconditional weekly backups
+├── .last_backup_state   ← DB fingerprint from last backup run
+└── backup.log      ← all run output
+```
+
+## Scripts
+```
+scripts/
+├── backup.sh       ← main backup script
+└── setup_cron.sh   ← installs / updates cron entries (idempotent)
+```
+
+## Schedule
+| Cron | Mode | Behaviour |
+|------|------|-----------|
+| `0 2 * * *` (daily 02:00) | `daily` | Compares DB fingerprint; skips if nothing changed |
+| `0 3 * * 0` (Sunday 03:00) | `weekly` | Always dumps; ignores fingerprint |
+
+To re-install cron entries after a path change:
+```bash
+./scripts/setup_cron.sh
+```
+
+## Backup Format
+Files are `pg_dump --format=custom --compress=9` (`.pgdump`).
+
+**Restore a backup:**
+```bash
+# Restore into a running container
+docker exec -i experiments_postgres pg_restore \
+  -U expuser -d experiments_db --clean \
+  < /home/sam/synology/Backups/Experiments-DB-Backup/daily/<file>.pgdump
+
+# Or restore to a fresh database
+docker exec -i experiments_postgres createdb -U expuser experiments_db_restore
+docker exec -i experiments_postgres pg_restore \
+  -U expuser -d experiments_db_restore \
+  < /path/to/file.pgdump
+```
+
+## Change Detection
+The daily run fingerprints the database as:
+```
+<experiments count>,<animals count>,<daily_statuses count>,
+<daily_analyses count>,<session_files count>,<latest audit_log timestamp>
+```
+Any insert, update, or delete on any table shifts this string and triggers a backup.
+
+## Retention Policy
+| Type | Keep |
+|------|------|
+| Daily | 5 most recent |
+| Weekly | 2 most recent |
+
+Older files are automatically deleted after each successful dump.
+
+## Manual Run
+```bash
+# Force a backup right now (ignores change detection)
+./scripts/backup.sh weekly
+
+# Run change-detect check manually
+./scripts/backup.sh daily
+```
+
+## Verify Cron Is Installed
+```bash
+crontab -l | grep ExpDB
+```