refactor(LaunchButtons): replace Pippin shell button with copy path to clipboard

[malaporte]

Summary

Removes the conditional Pippin shell action button from the worktree card launch buttons and replaces it with an always-visible button that copies the worktree path to the clipboard.

Changes

• Removed pippinPath state and the useEffect that fetched it via system:pippinPath RPC
• Removed handlePippinShell handler and launch:pippinShell RPC call
• Replaced IconPrison import with IconCopy from @tabler/icons-react
• Added handleCopyPath using navigator.clipboard.writeText(worktreePath)
• New button is always visible (no conditional rendering) with a "Copy path" tooltip

Testing

Typechecked with bun run typecheck — no errors. The clipboard write is a pure renderer-side browser API call with no backend dependency.

Reviewer Notes

The Pippin-related RPC handlers (system:pippinPath, launch:pippinShell) remain in the backend — this PR only removes the UI surface. Those can be cleaned up in a follow-up if Pippin support is being dropped entirely.

[github-actions]

🎉 This PR is included in version 2.11.0 🎉

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