fix(hub): mark bootstrap Inbox as SYSTEM_INBOX

Alpha silo bootstrap created the root Inbox without kind=SYSTEM_INBOX, so
Feishu card project creation tried to insert a second Inbox and hit the
sibling-name unique index. Tag the bootstrap folder correctly and promote
any legacy root Inbox on ensure.

hub/src/deployment/bootstrap-silo.ts

@@ -250,6 +250,7 @@ async function initializeSilo(
       data: {
         organizationId: input.organization.id,
         name: "Inbox",
+        kind: "SYSTEM_INBOX",
         sortKey: "000000",
       },
     });