Control channels block data port alignment

### Feature Summary

Port alignment counts every channel registered on the port, including control channels. Control channels do not carry the data marker, so a port containing one data channel and one control channel can never complete alignment.

Before: data marker arrives -> control channel remains missing -> port does not align

After: data marker arrives -> only data channels are evaluated -> port aligns

Reproduction evidence:

1. Register one data channel and one control channel on the same input port.
2. Send a port alignment marker on the data channel.
3. Observe that the marker is not aligned even though every data channel on the port has reported.

A direct run on main produced:

```text
data_channels= 1
port_channels= 2
data_marker_aligned= False
alignment_state_retained= False
```

Version and commit evidence:

1.3.0-incubating-SNAPSHOT (main)

**Commit Hash**

70c21145887920528d7d5540e3fb790b43e8b759

**What browsers are you seeing the problem on?**

Not browser-specific.

**Relevant log output**

None.

### Proposed Solution or Design

After: data marker arrives -> only data channels are evaluated -> port aligns

### Affected Area

Workflow Engine (Amber)