fix: only decrypt events with actual encrypted content

Use applesauce Helpers.hasHiddenContent() instead of checking for
any content. This properly detects encrypted content and avoids
sending unnecessary decrypt requests to Amber for events that just
have plain text content.

Before: (evt.content && evt.content.length > 0)
After: Helpers.hasHiddenContent(evt)

Result:
- Only events with encrypted content sent to Amber
- Reduces unnecessary decrypt requests
- Faster bookmark loading

src/services/bookmarkProcessing.ts

@@ -173,7 +173,7 @@ export async function collectBookmarksFromEvents(
     )
 
     // Schedule decrypt if needed
-    if (signerCandidate && ((Helpers.hasHiddenTags(evt) && !Helpers.isHiddenTagsUnlocked(evt)) || (evt.content && evt.content.length > 0))) {
+    if (signerCandidate && ((Helpers.hasHiddenTags(evt) && !Helpers.isHiddenTagsUnlocked(evt)) || Helpers.hasHiddenContent(evt))) {
       decryptJobs.push({ evt, metadata })
     } else {
       // Check for already-unlocked hidden bookmarks