032: fix get_dashboards_page_async -> get_dashboards_page (method renamed during async migration)

get_dashboards_page_async() no longer exists — the sync/async split was
removed and the method is now simply get_dashboards_page() (already async).
Calls in dashboard slug resolution and git helpers were using the old name.
This caused AttributeError at runtime, making all slug-based dashboard
lookups fail with 'Dashboard not found'.

backend/src/api/routes/dashboards/_helpers.py

@@ -98,7 +98,7 @@ async def _find_dashboard_id_by_slug_async(
 
     for query in query_variants:
         try:
-            _count, dashboards = await client.get_dashboards_page_async(query=query)
+            _count, dashboards = await client.get_dashboards_page(query=query)
             if dashboards:
                 resolved_id = dashboards[0].get("id")
                 if resolved_id is not None:

backend/src/api/routes/git/_helpers.py

@@ -175,7 +175,7 @@ async def _find_dashboard_id_by_slug_async(
 
     for query in query_variants:
         try:
-            _count, dashboards = await client.get_dashboards_page_async(query=query)
+            _count, dashboards = await client.get_dashboards_page(query=query)
             if dashboards:
                 resolved_id = dashboards[0].get("id")
                 if resolved_id is not None: