home(feed): rename "View Original »" link to "Read More..."

The Latest section was showing "View Original »" for imported posts and
opening every click in a new tab, even though the /api/public/posts
endpoint doesn't expose an externalUrl — every link actually went to
the internal /articles/<slug> page. Two changes:

- Link text is now "Read More..." for every article in the feed.
- target="_blank" only applies when article.externalUrl is actually
  populated (currently never, but keeps the door open for cross-site
  syndication later). Internal /articles/<slug> links now open in the
  same tab as the user expects.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/home-page/components/ArticleFeed.tsx

@@ -560,7 +560,9 @@ export default function ArticleFeed() {
                 const articleHref = isImported && article.externalUrl
                   ? article.externalUrl
                   : `/articles/${article?.slug}`;
-                const linkProps = isImported ? { target: "_blank", rel: "noopener noreferrer" } : {};
+                const linkProps = isImported && article.externalUrl
+                  ? { target: "_blank", rel: "noopener noreferrer" }
+                  : {};
 
                 // Mobile in-feed ad after every Nth article (skip if last item).
                 const isAdSlot =
@@ -621,7 +623,7 @@ export default function ArticleFeed() {
                           {...linkProps}
                           className="read-more flex-shrink-0 text-[11px] focus:outline-none focus-visible:underline"
                           aria-label={`Read more about ${article?.title}`}>
-                          {isImported ? "View Original »" : "Read More »"}
+                          Read More...
                         </Link>
                       </div>
                     </div>