fix(inbox): remove hardcoded 50-item limit from inbox list query

The ListInbox endpoint defaulted to LIMIT 50 while the frontend fetched
all items without pagination, causing items beyond the first 50 to be
silently dropped.

server/pkg/db/queries/inbox.sql

@@ -4,8 +4,7 @@ SELECT i.*,
 FROM inbox_item i
 LEFT JOIN issue iss ON iss.id = i.issue_id
 WHERE i.workspace_id = $1 AND i.recipient_type = $2 AND i.recipient_id = $3 AND i.archived = false
-ORDER BY i.created_at DESC
-LIMIT $4 OFFSET $5;
+ORDER BY i.created_at DESC;
 
 -- name: GetInboxItem :one
 SELECT * FROM inbox_item