chore: cursor-blink on empty-state placeholders

Adds the cursor-blink class to "no X" / "select a Y" placeholders across
core (calendar popup, board preview, search preview, detail split, notifs)
and plugins (chat, email, gitea, slideshow). Visual consistency with the
rest of the pixel-font UI.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/plugins/slideshow/slideshow.js

@@ -640,7 +640,7 @@ async function refreshGalleryPicker() {
     if (!images.length) {
         gp.grid.innerHTML = `<div class="col-span-full text-center py-16" style="grid-column:1/-1;">
             <i class="ph ph-image text-4xl text-t-dim mb-2 block"></i>
-            <p class="font-pixel text-[10px] text-t-dim">no images yet — upload above</p>
+            <p class="font-pixel text-[10px] text-t-dim cursor-blink">no images yet — upload above</p>
         </div>`;
         return;
     }
@@ -705,7 +705,7 @@ function renderPickerList(query) {
     picker.list.innerHTML = filtered.map(c => {
         const col = c.color ? `background:${c.color};` : '';
         return `<button class="slideshow-pick-row" data-pick-target="card:${escHtml(c.id)}"><span style="display:inline-block;width:8px;height:8px;${col}"></span><span style="flex:1;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;">${escHtml(c.title || '(untitled)')}</span></button>`;
-    }).join('') || `<div class="font-pixel text-[10px] text-t-dim px-2 py-2">no matches</div>`;
+    }).join('') || `<div class="font-pixel text-[10px] text-t-dim px-2 py-2 cursor-blink">no matches</div>`;
 }
 
 picker.search?.addEventListener('input', () => renderPickerList(picker.search.value));