unilab 1.3.0

What's Changed

• feat: mujoco 后端执行器切换到 mjbatch-uni(roadmap #1552) by @TATP-233 in #1562
• feat: complete per-env fixed model variant roadmap by @TATP-233 in #1568
• fix: remove duplicate reward episode metrics by @TATP-233 in #1570
• docs: document reward logging contract by @TATP-233 in #1571
• chore: prune redundant tests and remove legacy task-factory seam by @TATP-233 in #1573
• deps: unisim-core 1.4.0 and mjbatch-uni 0.2.1 by @TATP-233 in #1574
• release: unilab 1.3.0 by @TATP-233 in #1575

Full Changelog: v1.2.0...v1.3.0