fix(git): wire branch-picker merge-mode cancel + Escape

Merge mode had no exit: Escape was gated on branch_create_focused (false
in merge mode) and the painted 取消 hint was inert. Now:

- Escape is mode-based (branch_picker_open && mode != List → List), so it
  steps both create AND merge sub-modes back to the branch list
- new GitPanelHit::BranchPickerCancel: in merge mode a click anywhere but a
  branch row (incl. the 取消 hint) returns to the list

crates/op-editor-ui/src/widgets/git_panel.rs

@@ -117,6 +117,8 @@ pub enum GitPanelHit {
     BranchCreateInput,
     /// The inline create-branch submit button — create + switch.
     BranchCreateSubmit,
+    /// Cancel a create / merge sub-mode — return to the branch list.
+    BranchPickerCancel,
     /// The Remotes-section URL input box — focus it.
     RemoteInput,
     /// The Remotes-section "Set origin" button.

crates/op-editor-ui/src/widgets/git_panel_menus.rs

@@ -228,12 +228,23 @@ impl GitPanel<'_> {
             let bi = if merging { candidates[i] } else { i };
             let is_current = self.state.branches.get(bi) == self.state.branch.as_ref();
             let name = truncate(
-                self.state.branches.get(bi).map(String::as_str).unwrap_or(""),
+                self.state
+                    .branches
+                    .get(bi)
+                    .map(String::as_str)
+                    .unwrap_or(""),
                 BRANCH_NAME_MAX,
             );
             // Line 1 — branch name (always foreground; current branch is
             // signalled by the check, not by colour).
-            self.text(cx, &name, row.origin.x + 10.0, row.origin.y + 16.0, 12.0, t.foreground);
+            self.text(
+                cx,
+                &name,
+                row.origin.x + 10.0,
+                row.origin.y + 16.0,
+                12.0,
+                t.foreground,
+            );
             // Line 2 — last-commit subtitle (only the current branch's HEAD
             // commit is known here; others fall back to the no-commits label).
             let subtitle = if is_current {
@@ -361,7 +372,9 @@ impl GitPanel<'_> {
                         return Some(GitPanelHit::MergeBranch(candidates[i]));
                     }
                 }
-                Some(GitPanelHit::Inside)
+                // A click anywhere else in the popover (including the 取消
+                // hint) cancels merge mode back to the branch list.
+                Some(GitPanelHit::BranchPickerCancel)
             }
             GitBranchPickerMode::List => {
                 for (i, row) in self.branch_picker_row_rects(panel_rect).iter().enumerate() {

crates/op-host-native/src/widget_host/git_press.rs

@@ -240,6 +240,12 @@ impl WidgetHostNative {
                     panel.branch_picker_open = false;
                 }
             }
+            Some(GitPanelHit::BranchPickerCancel) => {
+                // Step a create / merge sub-mode back to the branch list.
+                panel.branch_picker_mode = GitBranchPickerMode::List;
+                panel.branch_create_draft.clear();
+                panel.branch_create_focused = false;
+            }
             Some(GitPanelHit::ShowWorkingDiff) => {
                 panel.pending_action = Some(GitPanelAction::ShowDiff(GitDiffTarget::WorkingTree));
             }

crates/op-host-native/src/widget_host/keyboard.rs

@@ -747,7 +747,13 @@ impl WidgetHostNative {
             self.mark_dirty();
             return true;
         }
-        if self.git_branch_create_focus_active() {
+        // …and a branch-picker sub-mode (create / merge): Escape steps it
+        // back to the branch list (the dropdown stays open). Driven off the
+        // mode, not input focus, so merge mode (no focused input) exits too.
+        if self.editor_state.editor_ui.git_panel.branch_picker_open
+            && self.editor_state.editor_ui.git_panel.branch_picker_mode
+                != op_editor_core::GitBranchPickerMode::List
+        {
             let panel = &mut self.editor_state.editor_ui.git_panel;
             panel.branch_picker_mode = op_editor_core::GitBranchPickerMode::List;
             panel.branch_create_draft.clear();