Route outbound Follow through EventProcessor for retry

send_follow now emits a Follow activity via emit_activity() instead of
inline HTTP POST. New ap_follow_handler delivers to the remote inbox;
EventProcessor retries on failure. Wildcard delivery handler skips
Follow type to avoid duplicate broadcast.

Also add /social/ index page to per-app social blueprint.

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

shared/infrastructure/ap_social.py

@@ -31,6 +31,16 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
             abort(403, "You need to choose a federation username first")
         return actor
 
+    # -- Index ----------------------------------------------------------------
+
+    @bp.get("/")
+    async def index():
+        actor = getattr(g, "_social_actor", None)
+        return await render_template(
+            "social/index.html",
+            actor=actor,
+        )
+
     # -- Search ---------------------------------------------------------------
 
     @bp.get("/search")