Bring up the USB gadget link (package 0b, Pi side and talos side)

The Pi presents NCM Ethernet and ACM serial from a configfs gadget, started by
robot-usb-gadget.service before networking. usb0 gets 10.55.0.2/30 with no
gateway through netplan, matched by interface name: a MAC match turns into
PermanentMACAddress= in networkd, which a gadget interface does not have, so it
stayed unmanaged. talos reaches the Pi at 10.55.0.2 (ping ~2.4 ms, SSH works)
through a NetworkManager profile, host/omarchy/robot-usb-link.sh, matched by the
gadget's fixed host MAC.

Also clamp the face's tunable parameters (focus sets a blur radius, persistence
divides) and fps, after a review flagged unvalidated node parameters.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AFN8nRRCiDiMN7ChBpHJhs

ros/hermes_face/test/test_render.py

@@ -99,3 +99,14 @@ def test_rotation_turns_the_frame_counter_clockwise(rotation):
 def test_bad_rotation_rejected():
     with pytest.raises(ValueError):
         FaceRenderer(rotation=45)
+
+
+def test_wild_parameters_are_clamped():
+    r = FaceRenderer(focus=1e9, persist_ms=0, intensity=-3, jitter=1e6, seed=0)
+    assert (r.focus, r.persist_ms, r.intensity, r.jitter) == (1.0, 5.0, 0.0, 5.0)
+    assert run(r, 1)[0].shape == (H, W, 3)
+
+
+def test_unknown_phosphor_rejected():
+    with pytest.raises(ValueError):
+        FaceRenderer(phosphor='P99')