[FEATURE]: Ability to pass in a sessionId for the opencode session to be tied to

[quuu]

Feature hasn't been suggested before.

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

Describe the enhancement you want to request

I have a multi-opencode orchestrator, and when i close it and re-open i'd like to resume the same session I was on previously.

opencode -c just opens globally the last session

and i know there's opencode -s <sessionId> but it requires me to somehow screen scrape and get that session id back

I'm proposing

opencode new -s <sessionId> and that sessionId being assigned to that instance for me to opencode -s <sessionId> and come back to it

this also works with opencode new -s "feature-dashboard" and let me come back to working on that feature on a specific project

(maybe the -s should be .git scoped)