Add per-app ActivityPub actors via shared AP blueprint

Each AP-enabled app (blog, market, events, federation) now serves its
own webfinger, actor profile, inbox, outbox, and followers endpoints.
Per-app actors are virtual projections of the same ActorProfile/keypair,
scoped by APFollower.app_domain and APActivity.origin_app.

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

infrastructure/factory.py

@@ -108,6 +108,12 @@ def create_base_app(
         from shared.infrastructure.oauth import create_oauth_blueprint
         app.register_blueprint(create_oauth_blueprint(name))
 
+    # Auto-register ActivityPub blueprint for AP-enabled apps
+    from shared.infrastructure.activitypub import AP_APPS
+    if name in AP_APPS:
+        from shared.infrastructure.activitypub import create_activitypub_blueprint
+        app.register_blueprint(create_activitypub_blueprint(name))
+
     # --- device id (all apps, including account) ---
     _did_cookie = f"{name}_did"