feat: Replace external storage with local file storage + auto cleanup

Media is now stored directly on the server disk (no external service).
Files are served via Express static middleware at /uploads/*.

Cleanup rules:
- Videos deleted immediately after successful publish to Facebook/Instagram
- Videos older than 7 days purged daily by cron job
- Images older than 30 days purged daily by cron job

Changes:
- server/services/minio.ts: replaced S3 client with local fs read/write
- server/index.ts: added static serving for /uploads/media, /logos, /stories
- server/services/media-purge.ts: new rules (images 30d, videos 7d)
- server/services/scheduler.ts: delete local videos after successful publish
- docker-compose.yml: add media_uploads, logos_uploads, stories_uploads volumes
- settings UI: removed credentials card, shows local storage info
- package.json: removed googleapis (unneeded)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -43,9 +43,6 @@ services:
       # Configuration FFmpeg Service
       FFMPEG_API_URL: http://ffmpeg-api:8000
       FFMPEG_API_KEY: ${FFMPEG_API_KEY:-socialflow-secret-ffmpeg-key}
-      # Configuration MinIO (stockage fichiers)
-      MINIO_ENDPOINT: ${MINIO_ENDPOINT:-http://minio:9000}
-      MINIO_PUBLIC_URL: ${MINIO_PUBLIC_URL:-http://localhost:9000}
     networks:
       - internal
       - nginx_default
@@ -55,6 +52,9 @@ services:
     volumes:
       - encryption_key:/app/.encryption-key-data
       - audio_uploads:/app/uploads/audio
+      - media_uploads:/app/uploads/media
+      - logos_uploads:/app/uploads/logos
+      - stories_uploads:/app/uploads/stories
     command: npm run start
 
   # Service FFmpeg dédié
@@ -78,6 +78,12 @@ volumes:
     driver: local
   audio_uploads:
     driver: local
+  media_uploads:
+    driver: local
+  logos_uploads:
+    driver: local
+  stories_uploads:
+    driver: local
 
 networks:
   # Réseau interne pour la communication DB <-> App