feat(maestro): move worktree choice behind advanced options

The worktree step ("+ new" plus the repository's existing worktrees) now
lives inside the collapsed "Advanced options" section in both the web form
and the TUI draft pane, so a plain spawn is command, project, name.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/src/worktreeStep.test.ts

@@ -108,6 +108,16 @@ describe("spawnForm worktree step (#95)", () => {
     expect(step(form).hidden).toBe(false);
   });
 
+  it("keeps the worktree step inside the collapsed Advanced options section", async () => {
+    const form = await mount([MAESTRO, WT_A]);
+    box(form, MAESTRO.path).click();
+    await drain();
+
+    const collapsible = form.querySelector<HTMLElement>(".wt-collapsible")!;
+    expect(collapsible.contains(step(form))).toBe(true);
+    expect(collapsible.hidden).toBe(true);
+  });
+
   it("lists '+ new' first and selected by default, then the project's worktrees", async () => {
     const form = await mount([MAESTRO, WT_A, WT_B]);
     box(form, MAESTRO.path).click();