Do not mark node READY when health check reports zero cpu or memory (#16511)

Instances reporting cpu=0 or memory=0 with no errors would be
transitioned to READY state. Treat zero cpu/memory as an error
so the node stays offline until a valid health check is received.

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

awx/main/models/ha.py

@@ -374,6 +374,11 @@ class Instance(HasPolicyEditsMixin, BaseModel):
             self.memory = new_memory
             update_fields.append('memory')
 
+        # Do not mark nodes READY if cpu or memory is zero
+        if not errors and self.node_type != Instance.Types.HOP and (not new_cpu or not new_memory):
+            errors = _('Health check for {} reported invalid values: cpu={}, memory={}').format(self.hostname, new_cpu, new_memory)
+            logger.warning(errors)
+
         if not errors:
             self.refresh_capacity_fields()
             self.errors = ''