feature: Support Opencode.session.update / AsyncOpencode.session.update

[dsillman2000]

Would it be possible to make the "update session" pattern easier? This is the only way to change properties about a session after it's been created (archive, rename, or change worktree), which requires directly using the "patch" method on Opencode/AsyncOpencode, or the _patch method on the corresponding SessionResource.

from pathlib import Path

from opencode_ai import Opencode
from opencode_ai.types.session import Session

OPENCODE_EXPERIMENTS_DIR = Path(__file__).parent.parent.absolute()

if __name__ == "__main__":
    opencode = Opencode(base_url="http://localhost:9000")
    session = opencode.session.create(
        extra_query={"directory": str(OPENCODE_EXPERIMENTS_DIR)},
        extra_body={"title": "my session ID is (tmp)"},
    )
    opencode.patch(
        "/session/" + session.id,
        cast_to=Session,
        options={
            "params": {"directory": str(OPENCODE_EXPERIMENTS_DIR)},
            "extra_json": {"title": f"my session ID is {session.id}"},
        },
    )