feat(nodes): add renewal cycle and auto-advance scheduling (#296)

- Add renewal_cycle field to nodes for tracking paid vs free cycles
- Implement auto-advance scheduling when renewal is processed
- Add migration test for renewal_cycle column
- Update dashboard to show renewal cycle count
- Add renewal status display on node detail page

vite-frontend/src/api/types.ts

@@ -6,6 +6,7 @@ export interface NodeApiItem {
   remark?: string;
   tags?: string;
   expiryTime?: number;
+  renewalCycle?: "month" | "quarter" | "year" | "";
   syncError?: string;
   [key: string]: unknown;
 }
@@ -221,6 +222,7 @@ export interface NodeMutationPayload {
   remark?: string;
   tags?: string;
   expiryTime?: number;
+  renewalCycle?: "month" | "quarter" | "year" | "";
   serverIp?: string;
   serverIpV4?: string;
   serverIpV6?: string;