* fix(g1): add video stream and camera_info to G1SimConnection

G1SimConnection was missing color_image and camera_info outputs,
so MuJoCo-rendered frames never reached the rerun bridge. Mirrors
the Go2 connection pattern: subscribes to video_stream(), publishes
camera_info in a background thread, and adds camera_optical TF frame.

* fix(g1): remove /g1/ topic prefix to match Go2 and rerun overrides

The rerun visual_overrides from #1334 used world/camera_info and
world/color_image (matching Go2), but the G1 transports used /g1/
prefixed topics. This mismatch meant the rerun bridge never applied
the camera_info pinhole overlay.

Remove the /g1/ prefix from color_image and camera_info transports
in the primitive blueprint and the SHM blueprint. Now matches Go2
convention and the rerun overrides work correctly.

* fix(g1): skip webcam camera_module in simulation mode

In sim, G1SimConnection now provides video from MuJoCo. The webcam
camera_module in the primitive was also publishing to color_image,
causing interleaved webcam + MuJoCo frames. Conditionally skip
camera_module when global_config.simulation is True.

* fix(g1): use correct MuJoCo camera intrinsics and add thread exit condition

- Replace hardcoded 1280x720 Go2 intrinsics with computed values from
  MuJoCo constants (320x240, FOV=45°) matching MujocoConnection pattern
- Add _stop_event to camera_info loop for clean shutdown

* fix(sim): increase MuJoCo video render resolution to 1280x720

* fix(g1): revert MuJoCo resolution, use Go2 camera intrinsics for rerun

MuJoCo framebuffer can't exceed 640 width without XML config. Reverted
render resolution to 320x240. Use the same 1280x720 camera intrinsics
as Go2 for rerun display scaling (matches Go2 sim behavior exactly).

* fix(sim): increase MuJoCo render resolution to 1280x720

Set offscreen framebuffer size in model XML to support the higher
resolution. Previously failed because MuJoCo's default offscreen
buffer is only 640 wide.

* Revert "fix(sim): increase MuJoCo render resolution to 1280x720"

This reverts commit f21d37b.