FabricBloc public site foundation

FabricBloc's public content should be easy for marketing to update and easy for engineering to verify. This repository starts that boundary with reviewed Markdown for long-form posts, structured JSON for reusable campaign and page copy, and a generated catalog that consuming sites can pin during builds.

The goal is not to create a permanent bottleneck around engineering. The goal is to keep authored content, review state, and production consumption explicit so development previews and production releases do not drift into separate copies of the same message.