Decide and execute: Spark-first theme getting-started

Problem: The theme docs still present Intro Bootstrap as the starter: getting-started clones it, the structure diagram shows sass/ and omits directories Spark uses, and Spark appears only in the AI-skills catalog. The public guides now lead with Spark, so the two doc surfaces recommend different starting points.

Evidence: content/docs/index.mdx getting-started step 2; the shared _view-intro-theme snippet injected into themes/index.mdx and urls-and-template-paths.mdx; Spark absent from theme-doc prose.

Done when (decision, then execution):

• A decision is recorded that Spark is the documented default starter (or explicitly not yet).
• If yes: getting-started and the structure pages lead with Spark, and Intro Bootstrap is marked as the legacy starter with its docs retained.

Start with content/docs/index.mdx and inspect the shared _view-intro-theme snippet used by themes/index.mdx and urls-and-template-paths.mdx. Compare how the current Intro Bootstrap guidance differs from Spark and record the starter decision. Done means the decision is documented and, if Spark is selected, the getting-started and structure pages lead with Spark while retaining Intro Bootstrap as legacy documentation.