Log hydration failures instead of swallowing them silently (AI)

hydrateArticleNow()'s catch-all discarded network, HTTP, and parsing
errors alike with no diagnostic, using the same fallback for all of
them. A real bug in parseFrontmatter()/deriveContentFields() would
silently leave an article title-less forever with no way to tell it
apart from a transient fetch blip. Now logged via console.error.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

js/discovery.js

@@ -294,7 +294,14 @@ async function hydrateArticleNow(stub) {
         const authoritative = { ...stub };
         Object.assign(stub, meta, authoritative, deriveContentFields(meta, content, stub.path), { hydrated: true });
         await setCacheEntry(stub.path, { mtime: stub.mtime, article: stub });
-    } catch { /* leave stub unhydrated — retried next time it's rendered */ }
+    } catch (error) {
+        // Leave stub unhydrated — retried next time it's rendered. Logged
+        // (not surfaced in the UI, which just shows the title-less card)
+        // so a persistent failure — a real bug in parseFrontmatter() or
+        // deriveContentFields(), not just a transient fetch blip — is still
+        // visible somewhere instead of silently retrying forever.
+        console.error(`Failed to hydrate article ${stub.path}:`, error);
+    }
     return stub;
 }