v2.4.1 — fixes from real-hardware testing (2026-10-17)

• get_vm_backup_snapshot_history on a standalone ESXi host answers instead of failing. Its error handler named
  vim.fault.InvalidArgument, a class pyVmomi does not have, so every call on ESXi ended in
  AttributeError: operation failed.. ESXi keeps no queryable task history; the tool now says so in
  history_unavailable and points at the vCenter that manages the host.
• list_active_tasks with limit keeps the newest tasks. It kept the oldest (57 tasks, limit=40 dropped the 17
  newest). Running and queued tasks come first, then newest first.
• get_datastore_capacity's view_note no longer blames a vCenter/ESXi gap on different VMs alone. On the test
  lab both listed the same 10 VMs and still reported different uncommitted space; the note now says how to tell the
  two cases apart (vm_count).
• list_all_clusters rows carry the cluster moid (also a CLI column), the id the vLCM tools take and their
  errors send you to look up.
• Error hints: doctor is suggested for connection, credential and proxy problems, not for a name that does not
  resolve or a bad argument. A reverse proxy answering HTML on the REST session call is named as such. Messages
  name MCP tools and parameters, with the CLI form in brackets.
• Gate: every pyVmomi class named in an except clause or isinstance() must exist (family smoke).