feat: support Docker volume-based JAR mounting for Docker-in-Docker

When CAMELEER_JAR_DOCKER_VOLUME is set, the orchestrator mounts the
named volume at the jar storage path instead of using a host bind mount.
This solves the path translation issue in Docker-in-Docker setups where
the server runs inside a container and manages sibling containers.

The entrypoint is overridden to use the volume-mounted JAR path via
the CAMELEER_APP_JAR env var.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/resources/application.yml

@@ -52,6 +52,7 @@ cameleer:
     routing-mode: ${CAMELEER_ROUTING_MODE:path}
     routing-domain: ${CAMELEER_ROUTING_DOMAIN:localhost}
     server-url: ${CAMELEER_SERVER_URL:}
+    jar-docker-volume: ${CAMELEER_JAR_DOCKER_VOLUME:}
   body-size-limit: ${CAMELEER_BODY_SIZE_LIMIT:16384}
   indexer:
     debounce-ms: ${CAMELEER_INDEXER_DEBOUNCE_MS:2000}