fix(maestro): default the worktree toggle off when the directory is itself a worktree (#91)

Picking a project row that is itself a linked git worktree used to
default 'Create git worktree' on, so spawning asked for a second
worktree of an already-checked-out branch and git refused. Both clients
now default the toggle off there: the session just runs in that existing
worktree with no worktree record (not adoption). Turning it back on by
hand still tries, per the issue's non-goal.

web/src/spawnFormWorktree.test.ts

@@ -18,6 +18,7 @@ const BRANCHES = [
  * its branch list is still in flight. */
 function stubFetch(opts?: {
   gateBranches?: (release: () => void) => void;
+  projects?: unknown[];
 }): string[] {
   const urls: string[] = [];
   const gated = new Promise<void>((resolve) => {
@@ -37,7 +38,7 @@ function stubFetch(opts?: {
         return new Response(JSON.stringify(BRANCHES), { status: 200 });
       }
       if (url.includes("/api/projects")) {
-        return new Response(JSON.stringify(PROJECTS), { status: 200 });
+        return new Response(JSON.stringify(opts?.projects ?? PROJECTS), { status: 200 });
       }
       return new Response(
         JSON.stringify({ hostname: "h", version: "0", home_dir: "/home/user", presets: [] }),
@@ -100,6 +101,34 @@ describe("spawnForm worktree defaults and branch picker (#61)", () => {
     );
   });
 
+  it("defaults the worktree toggle off for a row that is itself a worktree (#91)", async () => {
+    urls = stubFetch({
+      projects: [
+        {
+          path: "/home/user/wt-91",
+          name: "wt-91",
+          is_worktree: true,
+          base_repo: "/home/user/maestro",
+          last_activity: "2026-08-20T10:00:00Z",
+        },
+      ],
+    });
+    handle = createSpawnForm({ onSuccess() {} });
+    document.body.appendChild(handle.el);
+    for (let i = 0; i < 40; i++) await Promise.resolve();
+
+    handle.el
+      .querySelectorAll<HTMLButtonElement>(".project-row")
+      .forEach((row) => row.dataset.cwd === "/home/user/wt-91" && row.click());
+    await drain();
+
+    expect(handle.el.querySelector<HTMLInputElement>("input[name=worktree_enabled]")!.checked).toBe(
+      false,
+    );
+    expect(urls.some((u) => u.includes("/api/gitroot"))).toBe(false);
+    expect(handle.el.querySelector<HTMLElement>(".wt-body")!.hidden).toBe(true);
+  });
+
   it("still probes the gitroot for a free-text directory", async () => {
     const form = await mount();