#22 feat: add split torrent workspace and native update checks

Summary

• Replace the torrent table with a compact list beside a persistent details pane, with transfer metrics, file and peer views, pause/resume controls, and destination-aware search.
• Check desktop updates directly through Electrobun's public manifest. An exhausted GitHub REST API quota no longer blocks native updates; notifications, downloads, and explicit restart/install actions keep their existing behavior.
• Extend the update integration scenario to verify successful native checks with a GitHub API returning HTTP 403, zero REST requests, and recovery from native check errors.

Validation

• bun run tscheck
• bun run fix
• bun run test — 233 tests pass
• bun run build
• Targeted bunx --bun ultracite check for the update service and tests
• Update and native update-host integration tests — 15 scenarios pass
• bun run build:desktop
• bun run test:native and bun run test:background for UI/native changes
• Engine/lifecycle changes tested through public APIs with real peers in temporary directories
• Downloaded files preserved unless the user explicitly requests deletion
• CHANGELOG.md updated under Unreleased
• No credentials or personal data included
• AI-assisted code reviewed by a human

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Summary by cubic

Splits the torrent library into a compact list beside a persistent details pane, and routes desktop update checks through Electrobun's public manifest so GitHub API quota exhaustion no longer blocks updates.

• The list shows transfer metrics, destination-aware search results, and pause/resume controls; the details pane keeps files, peers, and trackers with independent scrolling.
• Native update checks no longer consume GitHub REST quota; existing notification, download, and restart/install flows are unchanged.
• Extended update integration tests to cover HTTP 403 responses, zero REST calls, and recovery from native check errors.