Add actor search with infinite scroll

Replace single WebFinger lookup with paginated search across cached
remote actors and local profiles. New _search_results.html partial
with htmx infinite scroll sentinel. Form submits via hx-get for
seamless pagination.

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

bp/social/routes.py

@@ -138,13 +138,50 @@ def register(url_prefix="/social"):
     async def search():
         actor = getattr(g, "_social_actor", None)
         query = request.args.get("q", "").strip()
-        result = None
+        actors = []
+        total = 0
+        followed_urls: set[str] = set()
         if query:
-            result = await services.federation.search_remote_actor(g.s, query)
+            actors, total = await services.federation.search_actors(g.s, query)
+            if actor:
+                following, _ = await services.federation.get_following(
+                    g.s, actor.preferred_username, page=1, per_page=1000,
+                )
+                followed_urls = {a.actor_url for a in following}
         return await render_template(
             "federation/search.html",
             query=query,
-            result=result,
+            actors=actors,
+            total=total,
+            page=1,
+            followed_urls=followed_urls,
+            actor=actor,
+        )
+
+    @bp.get("/search/page")
+    async def search_page():
+        actor = getattr(g, "_social_actor", None)
+        query = request.args.get("q", "").strip()
+        page = request.args.get("page", 1, type=int)
+        actors = []
+        total = 0
+        followed_urls: set[str] = set()
+        if query:
+            actors, total = await services.federation.search_actors(
+                g.s, query, page=page,
+            )
+            if actor:
+                following, _ = await services.federation.get_following(
+                    g.s, actor.preferred_username, page=1, per_page=1000,
+                )
+                followed_urls = {a.actor_url for a in following}
+        return await render_template(
+            "federation/_search_results.html",
+            actors=actors,
+            total=total,
+            page=page,
+            query=query,
+            followed_urls=followed_urls,
             actor=actor,
         )