#22344: feat(docker): add pre-built image mode for docker-setup

## What changed - Added `OPENCLAW_IMAGE_SOURCE` support in `docker-setup.sh` with interactive prompt for tty (1=local, 2=registry). - Wired image naming to image source: - `local` -> `openclaw:local` - `registry` -> `OPENCLAW_IMAGE` (defaults to `openclaw:latest`) - Skips `docker build` when `OPENCLAW_IMAGE_SOURCE=registry`; keeps onboarding/composition flow unchanged. - Persisted new env key in `.env` via `upsert_env`: `OPENCLAW_IMAGE_SOURCE`. - Updated Docker docs (`docs/install/docker.md`, `docs/zh-CN/install/docker.md`) to document the new option. - Added regression tests in `src/docker-setup.test.ts` for registry source and `.env` persistence. ## Why this fixes #22316 It enables Docker setup to use a pre-built image from registry instead of forcing a local rebuild, while keeping current local build behavior as the default. ## Tests run - `pnpm vitest run --config vitest.config.ts src/docker-setup.test.ts` - `pnpm test src/docker-setup.test.ts` ## Edge cases - Non-interactive shells default to `local` to avoid blocking prompts in CI. - `OPENCLAW_IMAGE_SOURCE` only accepts `local` or `registry`; invalid values fail fast with a clear error. - Custom image tag is supported via `OPENCLAW_IMAGE` when using registry source. <!-- greptile_comment --> <h3>Greptile Summary</h3> Added `OPENCLAW_IMAGE_SOURCE` environment variable to allow users to choose between building Docker images locally or using pre-built registry images. The implementation includes interactive prompts for TTY sessions and defaults to local builds in non-interactive environments. - Added `choose_image_source()` function with interactive prompt for image source selection - Conditional image naming: `registry` source uses `openclaw:latest` by default, `local` uses `openclaw:local` - Skips docker build step when using registry source - Persists `OPENCLAW_IMAGE_SOURCE` in `.env` file - Added comprehensive test coverage for registry source - Documentation updated in both English and Chinese <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk - The implementation is clean and well-tested. The logic correctly handles both interactive and non-interactive modes, validates input values, and maintains backwards compatibility by defaulting to local builds. The changes are isolated to Docker setup workflow and include appropriate test coverage. - No files require special attention _{Last reviewed commit: bdbddc9} <!-- greptile_other_comments_section --> <!-- /greptile_comment -->