mjlab v1.6.0

This release bumps mjlab to MuJoCo and MuJoCo Warp 3.11, broadens visual domain randomization to lights and textures, and fixes a family of partial-reset bugs that caused state leakage between environments.

Breaking changes

• CollisionCfg no longer silently defaults contype, conaffinity, condim, and priority to MuJoCo's values. All four must be set explicitly; add a ".*" catch-all entry for dict values that should cover every matched geom.
• CommandTerm._update_command gains an env_ids parameter (None for the regular per-step call, reset ids when called from reset()). Custom command terms must add it; construction raises a TypeError with migration instructions if it is missing.
• ViewerConfig is now keyword-only.

Visual domain randomization

Six new dr.light_* functions randomize light diffuse, specular, ambient, attenuation, cutoff, and exponent. LightCfg exposes the corresponding static fields. TextureCfg can now load textures from image files, and dr.mat_texid randomizes which texture fills a material slot. A new GeomCfg spec editor patches geom attributes (group, collision fields) by name pattern.

Partial-reset correctness

reset(env_ids=...) previously leaked state into environments that were not reset: commands advanced an extra step, observation buffers received a duplicate frame, and interval-event timers carried over from the previous episode. All three are fixed. auto_reset and an explicit reset() now produce identical state.

Quality of life

• The offscreen renderer operates on a model copy, so render-only tweaks (extent, shadows, reflections) no longer bleed into the simulation model.
• ViewerConfig gains geom_group and site_group for controlling which visualization groups the offscreen renderer draws.
• MetricsTermCfg supports reduce="sum" for reporting accumulated episode totals.
• init_velocity_prob no longer restores the pre-reset pose or teleports root velocity on mid-episode resamples.
• CircularBuffer lag retrieval clamps to the oldest retained frame instead of wrapping.
• Camera sensor caches are invalidated after sense(), fixing stale observations.

This release includes significant contributions from @bd-pmorais (visual domain randomization, GeomCfg, MuJoCo 3.11 bump) and @bd-mlutter (ViewerConfig improvements, offscreen renderer isolation, metrics).

Full changelog: v1.5.3...v1.6.0