Relocate Docker-based local browser controls to steel dev start/stop and update browser command descriptions/docs to point local usage to dev commands.

Adds repeatable cold/warm benchmark scenarios with budget thresholds and mock session API wiring for regression checks.

Switches Steel bootstrap injection to --cdp, preserves bare --auto-connect discovery, and rejects mixed attach flags. Bundles upstream daemon dist assets with vendored runtime, auto-sets AGENT_BROWSER_HOME for vendored execution, and adds runtime/cloud smoke validation scripts.

Adds a dependency guard script and wires it into build to prevent accidental playwright installs or lockfile drift away from playwright-core.

…nstall flow

- add --api-url support across browser lifecycle and passthrough bootstrap

- add steel dev install and explicit local runtime install/start/stop boundaries

- improve localhost local-mode guidance and add cloud integration + unit coverage

- add browser compatibility, migration, upstream sync, and reference index docs

- update generated CLI docs and docs generator option naming

- record authenticated cloud smoke pass in implementation plan