feat(quota): add tunnel traffic quota with daily/monthly limits (#291) (#308)

Implement per-tunnel traffic quota feature:
- Add TunnelQuota model with daily/monthly usage tracking
- Integrate quota enforcement into flow accumulation path
- Pause forwards and disable tunnel when quota exceeded
- Block new forward creation/resume when tunnel quota disabled
- Auto-reset daily/monthly windows at 00:05 via maintenance job
- Add manual reset API endpoint for admins
- Include quota config in tunnel backup/restore
- Add frontend UI for quota settings and usage display

Entire-Checkpoint: e629b27ca437

vite-frontend/src/api/index.ts

@@ -18,6 +18,7 @@ import type {
   UserMutationPayload,
   NodeMutationPayload,
   TunnelMutationPayload,
+  TunnelQuotaResetPayload,
   UserTunnelAssignPayload,
   UserTunnelListQuery,
   UserTunnelRemovePayload,
@@ -117,6 +118,8 @@ export const getTunnelById = (id: number) =>
   Network.post<TunnelApiItem>("/tunnel/get", { id });
 export const updateTunnel = (data: TunnelMutationPayload) =>
   Network.post("/tunnel/update", data);
+export const resetTunnelQuota = (data: TunnelQuotaResetPayload) =>
+  Network.post("/tunnel/quota/reset", data);
 export const deleteTunnel = (id: number) =>
   Network.post("/tunnel/delete", { id });
 export const diagnoseTunnel = (tunnelId: number) =>