Feature/drag to select cards

[NigamDevansh]

What this changes

• Feature: drag to select. Press in the shelf's empty space and drag a rectangle over cards to select them, like Finder. ⌘/Shift adds to the selection; the row scrolls when you hold at an edge. Pressing on a card or tab still drags it.
• Fix: search help panel. Its background changed with the pointer instead of showing the cards under it. It now blurs the cards beneath.
• Polish: smoother shelf close (quick fade and sink). After a drop onto a pinboard, only the held card stays selected.

How you tested it

vid 1 : search panel issue:

Screen.Recording.2026-10-02.at.9.55.06.PM.1.mov

vid 2 : drag to select feature:

Screen.Recording.2026-10-02.at.10.11.10.PM.mov

Ran on macOS 27, plus swift test --package-path CopyCore (new ShelfSelection tests).

---

• Every commit is signed off (git commit -s, or turn on the hook once with
  git config core.hooksPath .githooks). The DCO check enforces this. See
  CONTRIBUTING.md.
• Engine changes come with tests (swift test --package-path CopyCore)
• CopyCore/Package.resolved still pins GRDB, KeyboardShortcuts and Sparkle

[NigamDevansh]

Hi @tarikbc , add a feature of drag to select th cards along with this , fixed some hover issue and animation of closing of shelf.

please have a look... Thank you :)

btw , the new website looks super cool 🔥

[tarikbc]

Thanks again my friend!! Let's make the best open-source clipboard tool out there. 🤝