Opus 4.8 support

[aicodex]

I can't select Opus 4.8.
When I select default, it show Claude Opus 4.7 (1M context), and auto select to Opus 4.7.

[wsdct]

me too

[yiranxiaohui]

me too

[Lucasrvdl]

Me too

[AuroraMaster]

Me too

[gobeyondpty]

blocked due to #1265