chore(portfolio): classify machine control tower

[saagpatel]

What

• Adds _machine/machine-control-tower to the portfolio catalog as an active infrastructure/control-surface entry.

Why

• Keeps portfolio truth generation aware of the machine control tower root, not only its nested command-bin folder.

How

• Classifies the root entry with owner, lifecycle, criticality, maturity, and notes fields consistent with the existing catalog.

Testing

• Not run (catalog-only change; portfolio truth refresh will follow after merge).

Performance Impact

• None expected.

Risk / Notes

• Low risk; affects generated portfolio classification outputs only.