feat(macOS): Add trash sync toggle for FileProvider virtual files

[Flo-129]

Summary

• Add user-configurable option to enable/disable macOS Trash integration for FileProvider domains
• When enabled: deleted files go to macOS Trash, server trash visible in Finder
• When disabled: Finder shows "Delete Immediately" (files still recoverable from server)

Changes

• New "Integrate macOS Trash" checkbox in Virtual Files settings (macOS 13.0+)
• Per-account preference stored in NSUserDefaults
• Domain reconfiguration via remove/add cycle (supportsSyncingTrash is read-only after creation)
• Thread-safety improvements for concurrent domain registry access
• Cleanup of unused socket communication code (superseded by XPC)

Test plan

• Enable virtual files for an account
• Toggle "Integrate macOS Trash" option on
• Delete a file in Finder → verify it appears in macOS Trash
• Open Trash in Finder → verify server trash contents are visible
• Toggle option off → verify no crash occurs
• Delete a file → verify "Delete Immediately" behavior

Requirements

• macOS 13.0+ (option hidden on earlier versions)
• Virtual files must be enabled for the account

[i2h3]

Thank you for your new pull request! I will bring this up for discussion internally. 🤔 Personally, I think it is fine to have a checkbox for that feature toggle but it contradicts our design guidelines on the other hand. 😵‍💫 I need to check in with the others.

[oskardotglobal]

Could ya'll approve workflows so we can test the builds from CI?

[github-actions]

Artifact containing the AppImage: nextcloud-appimage-pr-9264.zip

Digest: sha256:e7eddbec74c0a8cb15dc350e6f59af362c26cc88e549cdfb407538f81e1bec9b

To test this change/fix you can download the above artifact file, unzip it, and run it.

Please make sure to quit your existing Nextcloud app and backup your data.

[github-actions]

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[Rello]

Hello @Flo-129
thank you for your contribution to the Desktop Client!

I want to update you, that the fix was implemented in a parallel PR. The reason is the deeper redesign work within the client which made merging this PR too complicated.

the upcoming 4.0.5 will have the new trash handling already. There will be no flags anymore. The client will only put locally deleted items to the trash. No server deleted items; no items of others...

thank you again for your contribution here...

#9323