refactor: deployment infrastructure cleanup (4 fixes)

1. Docker socket security: remove root group from Dockerfile, use
   group_add in docker-compose.yml for runtime-only socket access

2. M2M server communication: create ServerApiClient using Logto
   client_credentials grant with API resource scope. Add M2M server
   role in bootstrap. Replace hacky admin/admin login in
   AgentStatusService.

3. Async deployment: extract DeploymentExecutor as separate @Service
   so Spring's @Async proxy works (self-invocation bypasses proxy).
   Deploy now returns immediately, health check runs in background.

4. Bootstrap: M2M server role (cameleer-m2m-server) with server:admin
   scope, idempotent creation outside the M2M app creation block.

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

docker-compose.yml

@@ -133,6 +133,8 @@ services:
   cameleer-saas:
     image: ${CAMELEER_IMAGE:-gitea.siegeln.net/cameleer/cameleer-saas}:${VERSION:-latest}
     restart: unless-stopped
+    group_add:
+      - "0"
     depends_on:
       postgres:
         condition: service_healthy