fix: display cost during streaming, guard winbar against nil/zero crashes, and async providers for percentage#379

sudo-tee merged 4 commits into

sudo-tee:mainsudo-tee/opencode.nvim:mainfrom

CnsMaple:fix/cost-display-and-mode-switchCnsMaple/opencode.nvim:fix/cost-display-and-mode-switchCopy head branch name to clipboard