feat(app): Add WebStorm editor target (#220)

* Add WebStorm editor target

* Fix rebase type errors and add TODO date tag

- Await listAvailableEditorTargets() which became async on main
- Wrap sendAgentMessage callback to match Promise<void> return type
- Add TODO(2026-07) date to legacy editor target ids comment

---------

Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>

packages/app/src/hooks/use-preferred-editor.test.ts

@@ -14,6 +14,12 @@ describe("resolvePreferredEditorId", () => {
     expect(resolvePreferredEditorId(["explorer", "vscode"], "finder")).toBe("explorer");
   });
 
+  it("keeps unknown editor ids when they are still available", () => {
+    expect(resolvePreferredEditorId(["unknown-editor", "cursor"], "unknown-editor")).toBe(
+      "unknown-editor",
+    );
+  });
+
   it("returns null when no editors are available", () => {
     expect(resolvePreferredEditorId([], "cursor")).toBeNull();
   });