docs: clarify released server setup for VS Code

[AlexMikhalev]

The Docker quickstart pointed to an image repository that returns manifest unknown. Point to the published terraphim-ai image and document its required explicit role configuration and haystack dependencies instead of presenting an incomplete launch command.

The guide records a bounded check using the released VS Code extension 0.1.4 in VS Code 1.126.0 and a digest-pinned public server image: real role switching saved concern → cost → concern, and search fallback saved supplier through both autocomplete commands. It distinguishes native API checks from visible UI qualification.

Validation: independently reviewed documentation, parsed JSON examples matched the actual successful configuration, actual saved output readback, and git diff --check. No package, runtime, dependency or release changes.

[github-actions]

Documentation Preview

Your documentation changes have been deployed to:
https://34dfbfab.terraphim-docs.pages.dev

This preview will be available until the PR is closed.