feat: dagu backup DAG + pre-commit drift hook + sync 6 apps

Priority 1: Daily backup automation via Dagu DAG (~/dagu/dags/fn_backup.yaml,
schedule "0 3 * * *"). Backs up registry.db, each operations.db, and vaults
via rsync --link-dest. Fixes set -e arithmetic bugs in rotate_backups.sh and
backup_all.sh ((var++) returns 1 when var=0). Fixes && chain set -e bug in
vault rotation.

Priority 2: Pre-commit hook v2 chains scan_secrets + uses_functions audit.
New function git_hook_audit_app_drift_bash_infra blocks commits that touch
app code when that app has uses_functions drift. Allows corrective app.md-only
edits. Installed on fn_registry + 32 sub-repos.

Priority 3: Synced uses_functions in 6 sub-repo apps (commits in their own
repos): dag_engine, script_navegador, deploy_server, docker_tui,
auto_metabase, metabase_registry. Drift went from 7/12 to 4/12 apps.
Remaining drift = audit heuristic limitations (Python nested imports,
Go symbol name detection).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

bash/functions/infra/rotate_backups.sh

@@ -23,7 +23,7 @@ rotate_backups() {
                 esac
                 ;;
         esac
-        ((i++))
+        i=$((i + 1))
     done
 
     # Validar numericos
@@ -98,9 +98,9 @@ rotate_backups() {
 
     # Contar slots ocupados para el reporte
     local cnt_daily=0 cnt_weekly=0 cnt_monthly=0
-    for (( j = 0; j < daily; j++ ));   do [[ -e "$dir/daily.$j"   ]] && ((cnt_daily++));   done
-    for (( j = 0; j < weekly; j++ ));  do [[ -e "$dir/weekly.$j"  ]] && ((cnt_weekly++));  done
-    for (( j = 0; j < monthly; j++ )); do [[ -e "$dir/monthly.$j" ]] && ((cnt_monthly++)); done
+    for (( j = 0; j < daily; j++ ));   do [[ -e "$dir/daily.$j"   ]] && cnt_daily=$((cnt_daily + 1));   done
+    for (( j = 0; j < weekly; j++ ));  do [[ -e "$dir/weekly.$j"  ]] && cnt_weekly=$((cnt_weekly + 1));  done
+    for (( j = 0; j < monthly; j++ )); do [[ -e "$dir/monthly.$j" ]] && cnt_monthly=$((cnt_monthly + 1)); done
 
     echo "ROTATED daily=$cnt_daily weekly=$cnt_weekly monthly=$cnt_monthly dir=$dir"
 }