fix(landing-page): drop Homepage CTA from plugin detail page (#3129)

Per product feedback: the Homepage button (rendered when a plugin's
manifest carries a `homepage` field that differs from its
`sourceUrl`) sent visitors off to upstream-author or original-source
URLs before they had a chance to explore the plugin via Open Design
itself. On a marketing detail page that's a leak, not a feature.

Removes the conditional block that rendered
`<a class="btn btn-ghost">Homepage ↗</a>` between the GitHub link
and the Share button. The header-action row is now exactly three
controls everywhere: Use this plugin → · Find on GitHub → · Share ↗.

The `plugin.homepage` data field stays available on the
`BundledPluginRecord` shape since the in-app catalog row, JSON-LD,
and any future author-bio surface can still consume it. The
`pcopy.detailHomepage` i18n key (with full 18-locale coverage) stays
for the same reason — `PluginsCopy` is `Partial<>` everywhere and
removing it would mean a 18-locale block edit for zero functional
gain.

apps/landing-page typecheck stays at 0 errors.

Co-authored-by: Joey-nexu <joeylee12629@gmail.com>

apps/landing-page/app/pages/plugins/[slug]/index.astro

@@ -121,11 +121,17 @@ const jsonLd = [
         <a class="btn btn-ghost" href={plugin.sourceUrl} target="_blank" rel="noopener">
           {pcopy.detailFindOnGithub}
         </a>
-        {plugin.homepage && plugin.homepage !== plugin.sourceUrl && (
-          <a class="btn btn-ghost" href={plugin.homepage} target="_blank" rel="noopener">
-            {pcopy.detailHomepage}
-          </a>
-        )}
+        {/*
+         * The Homepage CTA was removed per product feedback: surfacing the
+         * upstream / author homepage on a marketing detail page led visitors
+         * away from Open Design before they explored the plugin in-app. The
+         * `plugin.homepage` field stays in the manifest reader so other
+         * surfaces (the in-app catalog, JSON-LD, future authored bios) can
+         * still consume it; the marketing CTA is the only call site that
+         * removed it. The unused `pcopy.detailHomepage` i18n key stays for
+         * the same reason — it's `Partial<>` everywhere and removing it
+         * would touch 18 locale blocks for no functional gain.
+         */}
         <button
           type="button"
           class="btn btn-ghost detail-share-trigger"