refactor(clipboard): own one clipboard backend [2/6]

[jamditis]

Before submitting

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• I searched existing issues and pull requests (including closed ones) so this isn't a duplicate
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This environment does not include a Rust toolchain or native desktop session. Compilation and platform clipboard tests are delegated to CI.

Description

Second PR in the v0.6.0 lightweight-launch stack; based on codex/v060-command-parser.

Creates one Tauri-managed ClipboardService that owns the arboard backend and routes snapshot capture, restoration, transcript writes, fallbacks, and tray copies through it. The existing transaction lock remains only for delivery ordering.

Platform behavior is preserved: X11 clipboard ownership stays alive, Wayland continues to use wl-copy, Windows transcript writes remain excluded from clipboard history, and mixed/unsupported snapshots still use the documented fallback. The Tauri clipboard plugin is removed, reducing Cargo.lock from 795 to 794 packages.

Related issues

Fixes #286

Testing

• Existing snapshot round-trip and platform-format tests remain attached to the owned backend.
• git diff --check passes.
• Rust tests, native clipboard smoke tests, and release-size comparison: CI/native runners required.

Screenshots / videos (optional)

Not applicable; native clipboard ownership only.

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-08-28T22:21:42.653631Z	c8a9374	PR opened

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[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: c8a9374ce8

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[jamditis]

Release coordination: keep this pull request open and do not merge it into main until AudioBud v0.6.0 is public. The signed candidate at e417154 is being replaced because both SBOMs contain placeholder file hashes. Merging now would change the release base and restart validation. Continue review and CI cleanup, then send the final green SHA.

[jamditis]

Release coordination note: protected v0.6.0 candidate run 33230355853 passed at a8f57a3. Keep pull requests 311 through 317 unmerged until v0.6.0 publication is complete. The Office clean Windows lane is requested to test artifact audiobud-windows-x86_64-v0.6.0-1: NSIS, MSI, portable signatures and installs, press-start/press-stop dictation, delivery, target lock, the v0.5.0 updater, and uninstall. Report exact evidence before any merge or publication.

[jamditis]

Release coordination update for August 31: AudioBud v0.6.0 remains frozen before tagging. Clean Windows validation of run 33230355853 is still required: NSIS, MSI, portable, press-start/press-stop dictation, delivery, target lock, startup, tray, quit, uninstall, and the v0.5.0 updater path. Keep PRs 311 through 317 unmerged. Reply only on PR 311 with availability, exact evidence, or a blocker so the test record stays in one thread.