修复 Studio 失败测试并新增合并门禁

把丢失的 box 录像放回 apps/studio/tests/data/，修掉第 3 节 3–10 号与两处过时测试桩，
注册 timing 标记并让根目录收集零错误；新增 tools/gate.ps1 与可选的 pre-push 钩子。
验证：studio 524 通过 19 跳过、shared 467 通过 18 跳过、ui_check 632 项 0 失败、gate.ps1 退出码 0。
细节见 docs/test-repair-plan.zh.md。

pyproject.toml

@@ -24,4 +24,12 @@ packages = []
 [tool.pytest.ini_options]
 testpaths = ["shared/tests", "apps/studio/tests", "apps/autocal/tests"]
 pythonpath = ["shared/src", "apps/studio/src", "apps/autocal/src"]
-addopts = "-q"
+addopts = "-q --strict-markers"
+# ``timing`` marks a test that measures wall-clock throughput. Those tests are true
+# statements about a real pipeline but false on a loaded machine, so the merge gate runs
+# ``-m "not timing"`` and they are run separately (see docs/test-repair-plan.zh.md §3 #12).
+# ``--strict-markers`` is what makes a typo'd marker an error instead of a silently
+# unselected test.
+markers = [
+  "timing: measures wall-clock throughput; excluded from the merge gate",
+]