Register Cursor access-review connector

Wire Cursor into the connector-provider registry as an API-key,
single-tenant connector using HTTP Basic auth, with no picker,
settings, or name resolver. Add the CURSOR enum value, its
migration, and the GraphQL enum binding so the provider is
accepted across the API surface.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/server/api/console/v1/graphql/connector.graphql

@@ -50,6 +50,7 @@ enum ConnectorProvider
         @goEnum(
             value: "go.probo.inc/probo/pkg/coredata.ConnectorProviderAnthropic"
         )
+    CURSOR @goEnum(value: "go.probo.inc/probo/pkg/coredata.ConnectorProviderCursor")
 }
 
 type ConnectorProviderInfo {