fix(release): run generate.py + mike build in the docs preview worktree

They ran in the caller's cwd — mike build would read the wrong
mkdocs.yml (or fail). Test now asserts the site lands in the worktree;
drops scripts/docs/site/.marker committed by accident.

Author: localpibox

scripts/docs/site/.marker

@@ -609,13 +609,14 @@ def cmd_release_docs_ready(*, assume_yes: bool, cons: Console) -> int:
     if not gen.is_file():
         cons.error(f"{gen} missing — {DOCS_BRANCH} branch out of date?")
         return 1
-    out, err, code = run_cmd([sys.executable, str(gen), "--tag", target])
+    out, err, code = run_cmd([sys.executable, str(gen), "--tag", target],
+                             cwd=str(work))
     if code != 0:
         cons.error(f"generate.py failed: {err.strip() or out.strip()}")
         return 1
     mike = shutil.which("mike")
     mike_cmd = [mike] if mike else [sys.executable, "-m", "mike"]
-    out, err, code = run_cmd(mike_cmd + ["build"])
+    out, err, code = run_cmd(mike_cmd + ["build"], cwd=str(work))
     if code != 0:
         cons.error(f"mike build failed: {err.strip() or out.strip()}")
         cons.error("Install docs tooling: "

scripts/localpibox/stack/release.py

@@ -228,6 +228,8 @@ def test_docs_ready_flags_and_pushes(tmpdir):
     # dev content is merged into docs on the remote
     doc = _g(remote, "show", "refs/heads/docs:doc/x.md").stdout
     assert doc == "content v1\n"
+    # mike/generate ran in the preview worktree, not the caller's cwd
+    assert (tmpdir / "preview" / "docs" / "site" / ".marker").is_file()
 
 
 def test_docs_ready_idempotent(tmpdir):