MCP DevBridge v0.7.1

Default task-based shell execution release. bash no longer exposes timeout_ms and every shell command starts as a background task that immediately returns task_id. Removed the separate start_task tool and the normal-vs-large task distinction. Task lifecycle is managed with get_task, wait_task, list_tasks, and cancel_task; wait_task only bounds polling and never limits execution. Tasks keep the same workspace/bash-session/safety policy, use bounded rolling output, and cancellation terminates the full process tree. Running tasks are not persisted across DevBridge/CodexPro restarts. Verification: 304 pytest tests passed, Ruff clean, Pyright 0/0, TypeScript build green, full npm run smoke green, npm run stress green, frozen staging smoke and detached-upgrade dry-run passed. Installer SHA-256: 30562bfcdb3b25bbb330d06aec028cefc735e917bf735aa6e436b6236af5ea3c.