home3: rename the small-joys OTD card "A good thing today" → "On this day"

Names the ritual (this date in history) rather than describing it; matches the
/onthisday page + engine. Hero tag becomes "{year} in history" (the old
"ON THIS DAY" there was now redundant with the eyebrow).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/routes/home3/+page.svelte

@@ -139,8 +139,8 @@
   {:else}
     <a class="joy joy-fact" href="/onthisday">
       <div class="joy-in">
-        <div class="tag"><span class="rule"></span><span class="tag-label">A good thing today</span></div>
-        <p class="fact-hero"><span class="year">{fact?.year ?? '1928'}</span> <span class="onthis">ON THIS DAY</span></p>
+        <div class="tag"><span class="rule"></span><span class="tag-label">On this day</span></div>
+        <p class="fact-hero"><span class="year">{fact?.year ?? '1928'}</span> <span class="onthis">in history</span></p>
         <p class="fact">{fact ? clip(fact.text, 96) : 'Penicillin was discovered by a happy accident.'}</p>
       </div>
     </a>