feat: preserve non-text clipboard content during paste-and-restore

[egsok]

Problem

When using clipboard-based paste methods (Ctrl+V, Shift+Insert, etc.), Handy saves the clipboard, writes transcribed text, sends the paste keystroke, then restores the original clipboard content. Currently it only handles plain text — read_text() returns an empty string for anything else.

This means if you had a screenshot, copied files, or rich HTML in the clipboard before transcribing, it was silently replaced with an empty string. Your clipboard content was lost.

Solution

Use arboard (already a transitive dependency via tauri-plugin-clipboard-manager, so zero extra compile cost) to detect and restore all clipboard formats:

Format	Before	After
Plain text	✅	✅
Images (screenshots)	lost	✅
HTML (rich text from browser)	lost	✅
Files (copied from Explorer/Finder)	lost	✅

Detection order is most-specific-first: files → image → HTML → text → empty. This prevents false matches (e.g., browser copies set both HTML and text fallback — text-first would lose formatting).

On Wayland, text restore still uses wl-copy for umlaut compatibility.

Files changed

• src-tauri/Cargo.toml — add arboard as direct dependency
• src-tauri/src/clipboard.rs — add SavedClipboard enum + save_clipboard()/restore_clipboard(), replace text-only save/restore in paste_via_clipboard()

Test plan

• Copy screenshot (Win+Shift+S / Cmd+Shift+Ctrl+4) → transcribe → verify screenshot is still in clipboard
• Copy plain text → transcribe → verify text is restored
• Copy rich HTML from browser → transcribe → paste into rich editor → verify formatting preserved
• Copy files in Explorer/Finder → transcribe → verify files still pasteable
• Empty clipboard → transcribe → clipboard stays empty
• Transcribed text still pastes correctly into target app
• CopyToClipboard setting still works (leaves transcribed text in clipboard, no restore)

[cjpais]

Curious, have you tested all of these, just want to make sure

I've tested a branch that tried this before without success so just curious. I am open to this for sure though

[egsok]

@cjpais yes, sir! Tested every case (pics, html, files) on Win11.

authored a similar PR for Openwhispr recently (OpenWhispr/openwhispr#381), Handy is even better suited for this because of use of arboard (so we get support for random files from explorer as well, unlike Openwhispr).

[cjpais]

@egsok thanks for confirmation for Win11 testing, I will test on MacOS and get back

This definitely should be merged assuming it works well, it should address #921

Bug fixes are always super helpful so thank you!

[egsok]

@cjpais cool! let me know if anything needs fixing

[cjpais]

One possible thing to consider, in case of regressions is adding a toggle to change back to the old method. Could be done in debug potentially. I will test this myself first, I would prefer not to have this path.