[schemaitat]

What this does

• Adds a launch and verification diagram to the home page and Design page.
• Replaces the Mermaid-only security diagram with a bundled SVG, and keeps both diagrams as local site assets.
• Fixes the MkDocs link hook so docs images resolve to the published site rather than GitHub source links.

Why

Mermaid did not render in the requested preview, and the first image attempt was rewritten to an unpublished GitHub URL. Checked-in SVGs render without a Mermaid runtime or a TechDocs add-on and work in the local preview.

Verification

• just check (Rust formatting, Clippy, Rust tests, syntax and 86 Node tests)
• just docs-build (strict MkDocs build)
• Local preview serves both SVGs with HTTP 200 and references them from Home, Design, and Security.