fix(linux): prevent Wayland wl-copy follow-up hangs on CachyOS KDE

[boeserwolf]

Before Submitting This PR

Please confirm you have done the following:

• I have searched existing issues and pull requests (including closed ones) to ensure this isn't a duplicate
• I have read CONTRIBUTING.md

If this is a feature or change that was previously closed/rejected:

• I have explained in the description below why this should be reconsidered
• I have gathered community feedback (link to discussion below)

Human Written Description

On CachyOS (Arch) with KDE Wayland, paste method Ctrl+Shift+V worked once, but Handy could freeze on the next transcription/paste cycle after a successful wl-copy.
The clipboard content was written correctly, but the app got stuck in the Wayland clipboard command path.
This patch makes the Wayland clipboard flow robust across repeated calls.

Related Issues/Discussions

Fixes #
Discussion:

Related: #769

Community Feedback

Bug reproduced and validated locally on CachyOS (Arch) KDE Wayland with repeated transcription calls and Ctrl+Shift+V.

Testing

• Built and tested on Linux Wayland (CachyOS/Arch + KDE).
• Reproduced: first wl-copy succeeds, next call can hang.
• Verified after fix: repeated transcription/paste cycles no longer hang.
• cargo check --manifest-path src-tauri/Cargo.toml passes.

Screenshots/Videos (if applicable)

N/A

AI Assistance

• No AI was used in this PR
• AI was used (please describe below)

If AI was used:

• Tools used: Codex (gpt-5.3-codex)
• How extensively: Assisted with debugging, patch creation, and validation steps.

[boeserwolf]

Closing in favor of #775, which is a clean branch from main containing only the wl-copy clipboard fix commits.