enhancement: Add navigation link to Scoring Methodology in AppHeader and AppFooter #274

DevImpact includes an in-depth /scoring-methodology page with diagrams explaining raw scores, diminishing returns, and normalization formulas. Currently, AppHeader only contains a link to /leaderboard, and AppFooter has no navigation links. Users cannot discover the methodology page unless they scroll to the bottom of comparison results.

Motivation

Transparency in scoring is one of DevImpact's core value propositions. Giving visitors direct access to the methodology from the header and footer builds trust and improves discoverability.

Tasks

• Add a navigation link to /scoring-methodology in src/components/layout/app-header.tsx.
• Add quick links in src/components/layout/app-footer.tsx (Home, Leaderboards, Scoring Methodology, GitHub).
• Add nav.methodology to src/locales/en.json and src/locales/ar.json.

Files to Check

• src/components/layout/app-header.tsx
• src/components/layout/app-footer.tsx
• src/locales/en.json & src/locales/ar.json