Add just design to open the design-system viewer

[morgmart]

What this does

Adds just design to start the existing design-system viewer and open it in your browser. It installs locked dependencies like the other development commands, without starting the desktop app or live relay broker.

Why it matters

The design system now has a short, discoverable command alongside just web and just desktop. Both existing commands stay unchanged.

How it works

Reuses the existing viewer's server and browser-opening configuration, with the argument-forwarding pattern from #109. The default port is 1442; use just design --port 1444 when it is occupied. The README and contribution guide document the command and Ctrl+C shutdown.

Verification

• Command listing, dry runs, and diff checks passed.
• Ran the actual command on the default and an alternate port: locked install, viewer response, transformed entry, and correct URL passed to the browser opener all passed. Browser opening was intercepted with a temporary capture script; a visible OS browser launch was not manually checked.
• Occupied default port fails clearly; Ctrl+C releases the server port.
• Independent focused source review found no actionable issues. Existing custom/project hooks were preserved and passed; their selectors correctly skipped unrelated source suites.
• No browser test cases added or removed. Full scan and native builds were not run for this command-only change; hosted CI and required human/code-owner approval remain pending.

[wesbillman]

Carl, an automated reviewer, commenting via Wes’s GitHub account.

No actionable findings. Reviewed head 1f0cac17813d08e3cbc1b1e93786f80c082e1b50 against base b49b6e3a03de6100cb7127c2ec785f276e480c65.

• The five-line recipe is appropriately scoped: it reuses the locked-install dependency and existing positional-argument convention, then invokes the existing design viewer. The documentation matches its configuration: port 1442, strict port conflicts, and the viewer-specific browser-opening path. This command selects the standalone config rather than the main app’s live-broker config.
• Independently checked the complete diff and command/config/viewer entry path. The exact-head extracted justfile passes command listing and default/alternate-port dry runs with pinned just 1.58.0; exact base-to-head git diff --check passes. These were source/dry-run checks, not a local server or browser run. The PR reports actual default/alternate-port, occupied-port, opener-URL and Ctrl+C checks; I did not independently repeat them. Visible OS browser launch remains unverified.
• Hosted JavaScript, browser measurements, DCO, Semgrep and zizmor checks pass. Rust/tool integration and four browser journey shards are still running; Windows native validation is skipped. Required human/code-owner approval remains outstanding. Those are merge/validation gates, not defects identified in this diff.

Posting a comment, not formal approval. No merge performed.