feat(marketing-site): American Dream cover band + narrative weave

- Cover: publisher-style belly band across the lower book cover using a
  compressed banner (2.2MB screenshot -> 60KB WebP, resized to display
  needs), cropped via a width-locked <img> + percentage offset so the
  wordmark stays legible rather than getting zoomed/cropped sideways.
  Compass + wordmark compacted into a row to make room.
- Copy: the theme woven through Field Notes, Contents, the Founding
  Sponsor tier, and one direct FAQ entry -- mostly oblique, since the
  cover already states it explicitly. Hero/Recipe/Capture/Footer left
  untouched on purpose.

marketing-site/components/Tiers.jsx

@@ -40,7 +40,7 @@ export default function Tiers() {
             <div className="t-unit">limited · final terms at launch</div>
             <div className="t-desc">
               A named acknowledgment in the guide, a private cohort seat, and a hand in shaping
-              the first edition.
+              the first edition — the ground floor of something you helped build.
             </div>
           </div>
         </div>