Add test showing cherry-pick copy/paste doesn't survive a worktree switch

The cherry-pick clipboard lives in GuiRepoState.Modes, and we keep a
separate GuiRepoState per worktree (RepoStateMap is keyed by the worktree
path). Switching worktrees swaps in that worktree's own state, whose
clipboard is empty, so pasting is disabled. The copied commits aren't
cleared; they're stranded on the previous worktree's state and reappear
when switching back.

pkg/integration/tests/test_list.go

@@ -490,6 +490,7 @@ var tests = []*components.IntegrationTest{
 	worktree.AssociateBranchRebase,
 	worktree.BareRepo,
 	worktree.BareRepoWorktreeConfig,
+	worktree.CherryPickAcrossWorktrees,
 	worktree.Crud,
 	worktree.CustomCommand,
 	worktree.DetachWorktreeFromBranch,

pkg/integration/tests/worktree/cherry_pick_across_worktrees.go

@@ -0,0 +1,63 @@
+package worktree
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var CherryPickAcrossWorktrees = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Copy a commit in one worktree and paste it in another worktree of the same repo",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig:  func(config *config.AppConfig) {},
+	SetupRepo: func(shell *Shell) {
+		shell.NewBranch("mybranch")
+		shell.EmptyCommit("base")
+		// the linked worktree's branch stays at "base"
+		shell.AddWorktree("mybranch", "../linked-worktree", "newbranch")
+		shell.EmptyCommit("one")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Commits().
+			Focus().
+			Lines(
+				Contains("one").IsSelected(),
+				Contains("base"),
+			).
+			Press(keys.Commits.CherryPickCopy)
+
+		t.Views().Information().Content(Contains("1 commit copied"))
+
+		t.Views().Worktrees().
+			Focus().
+			Lines(
+				Contains("(main worktree)").IsSelected(),
+				Contains("linked-worktree"),
+			).
+			NavigateToLine(Contains("linked-worktree")).
+			Press(keys.Universal.Select)
+
+		t.Views().Commits().
+			Focus().
+			Lines(
+				Contains("base"),
+			).
+			Press(keys.Commits.PasteCommits)
+
+		/* EXPECTED:
+		t.ExpectPopup().Alert().
+			Title(Equals("Cherry-pick")).
+			Content(Contains("Are you sure you want to cherry-pick the 1 copied commit(s) onto this branch?")).
+			Confirm()
+
+		t.Views().Information().Content(DoesNotContain("commit copied"))
+
+		t.Views().Commits().
+			Lines(
+				Contains("one"),
+				Contains("base").IsSelected(),
+			)
+		ACTUAL: */
+		t.ExpectToast(Equals("Disabled: No copied commits"))
+	},
+})