feat: admin area with customers, users, settings, audit log, service status (phase 5)

- customer CRUD wizard backend: per-system credential shapes validated via
  connector construction, AES-256-GCM at rest, write-only over the API
- ticketing connectors (jira/azure_devops/youtrack/demo) with test-connection
- user management: roles, disable (revokes sessions), force password reset,
  delete; self-demotion/disable/delete guards
- admin-editable runtime settings ({_id:app}) incl. atomizer URL override
- audit log written on every privileged mutation + filterable list API
- service status panel: mongo/atomizer/work-performer health + latency with
  late-bound breaker, sync and jobs status providers
- tabbed admin UI (customers wizard dialog, users table, settings, status, audit)
- compose: mongo nofile ulimit 64000 (1024 default crashed WiredTiger)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docker-compose.yml

@@ -4,6 +4,12 @@ services:
     restart: unless-stopped
     # modest cache so the whole stack fits comfortably on small hosts
     command: ["mongod", "--wiredTigerCacheSizeGB", "0.5"]
+    # WiredTiger needs far more FDs than the 1024 some hosts default to;
+    # running out crashes mongod with a WT_PANIC during file creation
+    ulimits:
+      nofile:
+        soft: 64000
+        hard: 64000
     # Mongo is reachable only on the compose network; never published to the
     # host (§12).
     volumes: