fix: synthesize timeline content for likes/bookmarks/reposts

Interaction types (likes, bookmarks, reposts) have no body content in
their JF2 properties. The timeline entry was created with empty content,
showing blank posts in Phanpy/Moshidon. Now synthesizes display content
(e.g. "Liked: https://...") matching backfill-timeline.js behavior.

lib/syndicator.js

@@ -224,7 +224,7 @@ export function createSyndicator(plugin) {
         // timelines (Phanpy/Moshidon). Uses $setOnInsert — idempotent.
         try {
           const profile = await plugin._collections.ap_profile?.findOne({});
-          const content = normalizeContent(properties.content);
+          const content = buildTimelineContent(properties);
           const timelineItem = {
             uid: properties.url,
             url: properties.url,
@@ -289,13 +289,51 @@ export function createSyndicator(plugin) {
 
 // ─── Timeline helpers ───────────────────────────────────────────────────────
 
-function normalizeContent(content) {
+/**
-  if (!content) return { text: "", html: "" };
+ * Build content from JF2 properties. Synthesizes content for interaction
+ * types (likes, bookmarks, reposts) that have no body text.
+ */
+function buildTimelineContent(properties) {
+  const content = properties.content;
+  if (content) {
     if (typeof content === "string") return { text: content, html: `<p>${content}</p>` };
+    if (content.text || content.html) {
       return {
         text: content.text || content.value || "",
         html: content.html || content.text || content.value || "",
       };
+    }
+  }
+
+  // Synthesize for interaction types
+  const esc = (s) => s.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;").replace(/"/g, "&quot;");
+  const likeOf = properties["like-of"];
+  if (likeOf) {
+    return {
+      text: `Liked: ${likeOf}`,
+      html: `<p>Liked: <a href="${esc(likeOf)}">${esc(likeOf)}</a></p>`,
+    };
+  }
+  const bookmarkOf = properties["bookmark-of"];
+  if (bookmarkOf) {
+    const label = properties.name || bookmarkOf;
+    return {
+      text: `Bookmarked: ${label}`,
+      html: `<p>Bookmarked: <a href="${esc(bookmarkOf)}">${esc(label)}</a></p>`,
+    };
+  }
+  const repostOf = properties["repost-of"];
+  if (repostOf) {
+    const label = properties.name || repostOf;
+    return {
+      text: `Reposted: ${label}`,
+      html: `<p>Reposted: <a href="${esc(repostOf)}">${esc(label)}</a></p>`,
+    };
+  }
+  if (properties.name) {
+    return { text: properties.name, html: `<p>${esc(properties.name)}</p>` };
+  }
+  return { text: "", html: "" };
 }
 
 function mapPostType(postType) {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@rmdes/indiekit-endpoint-activitypub",
-  "version": "3.10.1",
+  "version": "3.10.2",
   "description": "ActivityPub federation endpoint for Indiekit via Fedify. Adds full fediverse support: actor, inbox, outbox, followers, following, syndication, and Mastodon migration.",
   "keywords": [
     "indiekit",