Add evidence-driven GitHub Pages landing site

[icidade]

What changed

• adds a complete responsive landing page under docs/
• uses the supplied MiniCISO visual identity, hero illustration, architecture diagram, favicon, and social preview
• adds project positioning, engagement lifecycle, staff profiles, first-assessment guidance, evidence principles, architecture, open-source, documentation, and creator sections
• adds accessible navigation, visible focus states, reduced-motion support, semantic structure, and project-subpath-safe relative assets
• adds Open Graph and Twitter card metadata
• updates the README with the public project-site link
• documents local preview and GitHub Pages publication from main + /docs

Why

MiniCISO needs a public visual entry point that helps security engineers, maintainers, and technical leaders understand the operating model before moving into the repository and wiki.

Validation

• local HTTP response: 200
• all relative asset paths resolved locally
• documentation routes checked against the published wiki repository
• repository file links checked against the current main tree
• git diff --check passed
• reviewed for project-subpath-safe asset paths, secret/private-data exposure, keyboard focus, semantic headings, and reduced motion

Known limitations

• GitHub Pages is not configured yet; after merge, select Deploy from a branch → main → /docs in Settings → Pages
• browser-backed desktop/mobile screenshots could not be generated because the integrated browser was unavailable in the authoring session
• the repository's PowerShell validator could not complete because the local python command resolves to the Windows Store alias; the failure is unrelated to the static-site files