feat: auto-trigger scheduled agents + fix stale nextRun display

- Add background scheduler in entrypoint: calls /api/cron/agents every
  5 minutes to trigger due agents automatically
- Recalculate stale nextRun (past dates) in getAgents() so the display
  always shows a future time
- Agent card shows "En attente de déclenchement" instead of "il y a X"
  when nextRun is in the past

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

memento-note/docker-entrypoint.sh

@@ -4,5 +4,14 @@ set -e
 echo "Running Prisma migrations..."
 node ./node_modules/prisma/build/index.js migrate deploy
 
+# Background scheduler: call /api/cron/agents every 5 minutes
+(
+  sleep 60
+  while true; do
+    wget -q -O /dev/null --post-data='' "http://localhost:3000/api/cron/agents" 2>/dev/null || true
+    sleep 300
+  done
+) &
+
 echo "Starting server..."
 exec node server.js