Wire real FederationService + add page federation events

- Blog app now registers SqlFederationService (was stub/no-op)
- sync_single_page emits post.published/updated events for pages
- Updated shared submodule: fix sign_request in AP delivery handler

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

bp/blog/ghost/ghost_sync.py

@@ -1066,7 +1066,25 @@ async def sync_single_page(sess: AsyncSession, ghost_id: str) -> None:
         tag_obj = await _upsert_tag(sess, pt)
         tag_map[pt["id"]] = tag_obj
 
-    await _upsert_post(sess, gp, author_map, tag_map)
+    post = await _upsert_post(sess, gp, author_map, tag_map)
+
+    # Emit federation event for published pages
+    if post.status == "published" and post.user_id:
+        from shared.events import emit_event
+        from shared.infrastructure.urls import app_url
+        event_type = "post.published" if post.created_at == post.updated_at else "post.updated"
+        await emit_event(
+            sess,
+            event_type=event_type,
+            aggregate_type="Post",
+            aggregate_id=post.id,
+            payload={
+                "user_id": post.user_id,
+                "title": post.title or "",
+                "excerpt": post.custom_excerpt or post.excerpt or "",
+                "url": app_url("coop", f"/{post.slug}/"),
+            },
+        )
 
 
 async def sync_single_author(sess: AsyncSession, ghost_id: str) -> None:

services/__init__.py

@@ -24,5 +24,5 @@ def register_domain_services() -> None:
     if not services.has("cart"):
         services.cart = SqlCartService()
     if not services.has("federation"):
-        from shared.services.stubs import StubFederationService
-        services.federation = StubFederationService()
+        from shared.services.federation_impl import SqlFederationService
+        services.federation = SqlFederationService()