fix(deploy): use /ready/ healthcheck and /srv/mnemosyne path

- Change app healthcheck from /live/ to /ready/ to verify full
  readiness including dependencies (DB, Neo4j, S3)
- Increase healthcheck timeout from 5s to 10s to accommodate
  dependency checks
- Add S3 bucket connectivity check to readiness probe
- Update deployment documentation to use /srv/mnemosyne instead
  of /opt/mnemosyne as the compose project directory

docker-compose.yaml

@@ -106,9 +106,9 @@ services:
     volumes:
       - mnemosyne-media:/app/media
     healthcheck:
-      test: ["CMD", "curl", "-f", "http://localhost:8000/live/"]
+      test: ["CMD", "curl", "-f", "http://localhost:8000/ready/"]
       interval: 30s
-      timeout: 5s
+      timeout: 10s
       retries: 3
       start_period: 30s