Publish the searchable FDE Guide site

[davidahmann]

Outcome

Publishes a professional GitHub Pages projection of The FDE Guide without creating a second content corpus. Canonical repository Markdown remains the source of truth.

What changed

• Adds 15 focused reader routes for FDE, value, architecture, evaluation, security, readiness, operations, examples, templates, and research.
• Adds accessible responsive navigation, local search, a social card, structured metadata, canonical URLs, sitemap, crawler policy, and a generated machine index.
• Adds one missing human entry point for production AI security and action boundaries.
• Adds a SHA-pinned Pages build and deployment workflow plus deterministic site tests.
• Corrects retired issue and security links and protects local environment files from accidental contribution.
• Rebinds evaluation and release evidence to the exact dependency lock after adding the pinned renderer dependencies.

Verification

• npm ci --ignore-scripts
• npm test
• git diff --check
• actionlint .github/workflows/*.yml
• npm audit --audit-level=high
• staged-diff secret scan
• desktop and 390px browser QA, including search and console checks

Rollback

Revert this PR to remove the site generator and Pages workflow. The underlying Markdown guide and engineering kit remain independently usable.