fix(mobile): header menu and Git menu reach a thread's linked pull request#17717

@@ -52,6 +62,22 @@ export function ThreadHeader(
       icon: "point.topleft.down.curvedto.point.bottomright.up",
       onPress: props.onOpenGitInspector,
     });
+    if (linkedPullRequestAction !== null) {
+      actions.push({
+        accessibilityLabel: linkedPullRequestAction.label,
+        icon: "arrow.triangle.pull",
+        onPress:
+          linkedPullRequestAction.kind === "open"
+            ? () => {
+                void openPullRequest(linkedPullRequestAction.url).then((opened) => {
+                  if (!opened) {
+                    Alert.alert("Unable to open PR", "The pull request could not be opened.");
+                  }
+                });
+              }
+            : props.onOpenGitInspector,