feat: merge the PR-comment browser + editor CTAs into one line (#30)

* feat: merge the PR-comment browser + editor CTAs into one line

Replace the two stacked CTA lines (a '🌐 Explore … in your browser →' line and a
separate 'See this … in your editor: Open in VS Code →' line) with a single
sentence: 'Explore this PR's architecture in your browser or VS Code.' The
browser link only joins when webview_ready (head analysis committed, non-fork
PR); 'your' rides with the browser entry alone so it still reads right when only
the editor link is present ('… in VS Code'). Multiple editors render with an
Oxford 'or' ('browser, VS Code, or Cursor'). The ⚠️ health banner and the
proxy-only 'Get the extension' line stay separate.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* chore(codeboarding): update architecture analysis [skip ci]

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Co-authored-by: codeboarding[bot] <codeboarding[bot]@users.noreply.github.com>

Author: brovatten