Add per-app AP social UI for blog, market, and events

Lightweight social pages (search, follow/unfollow, followers, following,
actor timeline) auto-registered for AP-enabled apps via shared blueprint.
Federation keeps the full social hub. Followers scoped per app_domain;
post cards show "View on Hub" link instead of interaction buttons.

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

shared/infrastructure/factory.py

@@ -111,6 +111,11 @@ def create_base_app(
         from shared.infrastructure.activitypub import create_activitypub_blueprint
         app.register_blueprint(create_activitypub_blueprint(name))
 
+    # Auto-register per-app social blueprint (not federation — it has its own)
+    if name in AP_APPS and name != "federation":
+        from shared.infrastructure.ap_social import create_ap_social_blueprint
+        app.register_blueprint(create_ap_social_blueprint(name))
+
     # --- device id (all apps, including account) ---
     _did_cookie = f"{name}_did"