Add layout section items to View ribbon

[code-by-sia]

Summary

• Adds concrete View > Layout ribbon items for Normal, Page layout, Page break, Gridlines, Headings, and Formula bar.
• Splits View ribbon controls into small PrintControls and LayoutControls components.
• Adds regression coverage for View tab layout items and toggle state.
• Regenerates the GitHub Pages build assets.

Closes #49.

Verification

• npm test
• npm run typecheck
• npm run build

Note: npm run build still reports the existing direct eval warning in src/lib/core/formula/Evaluator.ts; build succeeds.