## Summary

<!-- What does this PR do? One or two sentences. -->

## Why

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What problem does this solve, or what use case does it enable?
Link related issues here: "Closes #123", "Refs #456".
-->

## Type of change

- [ ] Bug fix
- [ ] New feature
- [ ] Refactoring (no behavior change)
- [ ] Documentation
- [ ] Tests only
- [ ] Build / CI / tooling
- [ ] Other

## Areas affected

- [ ] Frontend (UI / panel pages)
- [ ] Backend (API endpoints, login, settings)
- [ ] Xray config generation
- [ ] Subscription (share links / Clash / JSON)
- [ ] Statistics / traffic counters
- [ ] Database / migrations
- [ ] Install / upgrade script
- [ ] Docker image
- [ ] Multi-node (sub-nodes)
- [ ] Telegram bot

## How was this tested?

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Concrete steps the reviewer can repeat. For UI changes: which page,
which actions, which browser. For backend: which endpoint, which payload,
which response. Mention any new unit/integration tests added.
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## Screenshots / recordings

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## Breaking changes

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Does this change require existing users to update their config, run a
migration, or change their API calls? If yes, describe the migration path.
Write "None" if there are no breaking changes.
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## Checklist

- [ ] I tested the change locally and confirmed the described behavior.
- [ ] I added or updated tests for the new behavior (when applicable).
- [ ] `go build ./...` and the test suite pass locally.
- [ ] For frontend changes: `npm run lint`, `npm run typecheck`, and `npm run build` pass.
- [ ] I updated the Wiki / README / API docs if user-facing behavior changed.
- [ ] My commits follow the project's existing message style.
- [ ] I have no unrelated changes mixed into this PR.