Tuning: the CI waits may be zero

The live review test sets ci_grace_s: 0, which the shared tuning parser
refused (every number had to be positive). A field now opts in to zero
with metadata {"zero": True}; ci_wait_s and ci_grace_s do.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J5Utyfzw7gF7UhjRDEtjTk

nisse-review/tests/test_review.py

@@ -431,6 +431,21 @@ def test_a_repository_pattern_must_be_owner_slash_name(tmp_path: Path) -> None:
             ReviewConfig.from_tree({**tree, "repositories": [bad]}, {})
 
 
+def test_the_ci_waits_may_be_zero(tmp_path: Path) -> None:
+    # The live test's repository has no CI: it reviews with no grace at all.
+    from nisse_review.config import ReviewConfig
+
+    tree = {
+        "state_db": str(tmp_path / "s.db"),
+        "llm": {"base_url": "http://llm", "token": "k"},
+        "roles": {"reviewer": "local", "expert": "frontier"},
+        "gitea": {"url": "https://g", "token": "t", "operators": ["don"]},
+        "tuning": {"review": {"ci_wait_s": 0, "ci_grace_s": 0}},
+    }
+    review = ReviewConfig.from_tree(tree, {}).tuning.review
+    assert (review.ci_wait_s, review.ci_grace_s) == (0, 0)
+
+
 def test_diff_lines_are_the_heads_lines_a_diff_shows() -> None:
     diff = (
         "--- a/x.py\n+++ b/x.py\n@@ -1,3 +1,4 @@\n a\n-b\n+c\n+d\n e\n"