Fix follower links, HTMX follow/unfollow, update shared submodule

- Follower profile links now go to https://domain/@username (web profile)
  instead of the AP actor URL which 404s
- Follow Back/Unfollow buttons update via HTMX without full page refresh
- Update shared submodule to decoupling branch with new protocol methods

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

bp/social/routes.py

@@ -157,6 +157,8 @@ def register(url_prefix="/social"):
             await services.federation.send_follow(
                 g.s, actor.preferred_username, remote_actor_url,
             )
+        if request.headers.get("HX-Request"):
+            return await _actor_card_response(actor, remote_actor_url, is_followed=True)
         return redirect(request.referrer or url_for("social.search"))
 
     @bp.post("/unfollow")
@@ -168,8 +170,34 @@ def register(url_prefix="/social"):
             await services.federation.unfollow(
                 g.s, actor.preferred_username, remote_actor_url,
             )
+        if request.headers.get("HX-Request"):
+            return await _actor_card_response(actor, remote_actor_url, is_followed=False)
         return redirect(request.referrer or url_for("social.search"))
 
+    async def _actor_card_response(actor, remote_actor_url, is_followed):
+        """Re-render a single actor card after follow/unfollow via HTMX."""
+        remote_dto = await services.federation.get_or_fetch_remote_actor(
+            g.s, remote_actor_url,
+        )
+        if not remote_dto:
+            return Response("", status=200)
+        followed_urls = {remote_actor_url} if is_followed else set()
+        # Detect list context from referer
+        referer = request.referrer or ""
+        if "/followers" in referer:
+            list_type = "followers"
+        else:
+            list_type = "following"
+        return await render_template(
+            "federation/_actor_list_items.html",
+            actors=[remote_dto],
+            total=0,
+            page=1,
+            list_type=list_type,
+            followed_urls=followed_urls,
+            actor=actor,
+        )
+
     # -- Interactions ---------------------------------------------------------
 
     @bp.post("/like")