[FEATURE]: Ability to set thinking level when launching via cli args

[raza-jamil-reckon]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Currently when launching opencode via cli, we can specify the model but not the effort/thinking level, it will default to whatever is in opencode config which is not very helpful. We want different thinking levels for different tasks as we launch new opencode sessions for review, pull request creation and watching etc.

Something like:

opencode --model openai/gpt-5.6-sol --thinking low