fix(css): scope final-cta grid to inner section-shell wrapper

Move display:grid and gap from .final-cta to .final-cta > .section-shell
so the grid context is applied to the correct container element, not the
outer section. Wrap final-cta content in index.html with a section-shell
div accordingly. Also fix .no-results bottom padding that was missing.

Co-Authored-By: Claude <[email protected]>