feat(manager): add remote VM support via NEXUS_SERVER_HOST

- config.py: add NEXUS_SERVER_HOST env var for cross-VM deployment
- health_service.py: graceful Redis failure when only localhost-bound
- systemd service: document remote VM configuration
- README: add dedicated 'VM separada' installation section
- .env.example: new file with remote connection examples

manager/services/health_service.py

@@ -8,7 +8,7 @@ import psycopg2
 import redis
 from config import (
     MASTER_DB_URL, REDIS_URL, POS_URL, DASHBOARD_URL, QUART_URL,
-    TENANT_DB_URL_TEMPLATE
+    TENANT_DB_URL_TEMPLATE, NEXUS_SERVER_HOST
 )
 
 
@@ -31,7 +31,7 @@ def check_postgresql():
 
 
 def check_redis():
-    """Check Redis connectivity."""
+    """Check Redis connectivity. May be unreachable if Redis only binds to localhost."""
     try:
         r = redis.from_url(REDIS_URL, socket_connect_timeout=3)
         info = r.info()
@@ -41,6 +41,11 @@ def check_redis():
             "used_memory_human": info.get("used_memory_human", "?"),
             "connected_clients": info.get("connected_clients", 0)
         }
+    except redis.ConnectionError:
+        return {
+            "status": "warning",
+            "error": "Redis unreachable. If manager runs on a separate VM, ensure Redis binds to 0.0.0.0 or a VPN interface, or that a tunnel is active."
+        }
     except Exception as e:
         return {"status": "error", "error": str(e)}
 
@@ -121,6 +126,10 @@ def check_systemd_service(service_name):
 def get_full_health_report():
     """Aggregate health report for all services."""
     return {
+        "_meta": {
+            "nexus_server_host": NEXUS_SERVER_HOST,
+            "note": "disk/memory are local to this manager VM. PostgreSQL/HTTP checks target the remote Nexus server."
+        },
         "postgresql": check_postgresql(),
         "redis": check_redis(),
         "pos": check_http_service("pos", POS_URL),