Misleading per-frame WebRTC warning when IsaacSimCamera has WebRTC disabled

[Miical]

When an IsaacSimCamera is configured with enable_webrtc: false, the camera logs a warning on every valid frame:

[IsaacSimCamera] Failed to encode to WebRTC for head_camera
[IsaacSimCamera] Failed to encode to WebRTC for left_wrist_camera
[IsaacSimCamera] Failed to encode to WebRTC for right_wrist_camera

This happens even though WebRTC is intentionally disabled. The frame is still valid and ZMQ publishing can be working normally, so the warning is misleading and floods the logs.

Reproduction

Use an Isaac Sim camera config like:

head_camera:
  enable_zmq: true
  enable_webrtc: false

Then run the Isaac Sim image server / simulator with cameras enabled.

Expected behavior

If enable_webrtc is false, the camera should skip writing to the WebRTC buffer and should not log a warning.

Likely cause

In src/teleimager/image_server.py, IsaacSimCamera logs a warning in the else branch:

if self._enable_webrtc:
    self._webrtc_buffer.write(frame_data)
else:
    logger_mp.warning(...)

The else branch represents the configured-disabled state, not a failure.

Suggested fix

Remove the else warning:

if self._enable_webrtc:
    self._webrtc_buffer.write(frame_data)