fix(sisyphus-task): complete overhaul of background agent model handling and sync mode#655

Gladdonilli wants to merge 2 commits intocode-yeongyu:devcode-yeongyu/oh-my-opencode:devfrom

Gladdonilli:fix/thinking-model-completionGladdonilli/oh-my-opencode:fix/thinking-model-completionCopy head branch name to clipboard