i18n: Simplified Chinese reasoning-effort labels collapse two levels

Translation issue

The Simplified Chinese labels for the reasoning-effort picker do not preserve the six distinct English levels.

English order:

Light -> Medium -> High -> Extra High -> Max -> Ultra

Current Simplified Chinese labels visibly read:

轻度 -> 中 -> 高 -> 极高 -> 最高 -> 极高

That makes Extra High and Ultra both appear as 极高, so the last level looks like a duplicate and the ordering becomes unclear.

Please choose distinct Chinese terminology for all six levels while preserving their order. Screenshots comparing the Chinese and English pickers are attached in a follow-up comment.