fix(ci): run ruff format, and record run 5 at 90% pair-correct

CI was red on `ruff format --check`: 23 files. I ran `ruff check` after every
change this session and never once ran `ruff format --check`, though CI runs
both. Lint passing is not formatting passing, and I treated one as evidence for
the other for the whole session.

Formatting applied. The full CI sequence now reproduces locally: format, lint,
mypy over 94 files, 735 tests, three gates byte-identical, compileall, and the
semantic job's 16 marked tests.

Also records run 5 of the pipeline measurement, which the vampi fix lifted as
predicted:

                       hunter (K=5)   pipeline (K=1)
  pair-correct              76.7%          90.0%
  leak                      12.3%           6.7%
  detection                    --          96.7%
  cost                     ~$0.69        $0.0068

27 of 30 pairs. Five runs, each step from a measurement contradicting an
assumption: 73.3 (no pipeline path) -> 73.3 (routing fixed, IDENTICAL, which
exposed the discarded verdict) -> 80.0 (residual question matched to its
arbiter) -> 86.7 (aiohttp settings) -> 90.0 (dominance question no longer
contradicting its own evidence).

One miss left: dsvpwa-dsvpwa-main, whose setting is an argparse --ssl default
rather than a security-setting call. Out of reach before the settings work and
still is; contorting the arbiter around one pair would be worse than the miss.

The caveat is recorded beside the number: 30 pairs of one slice, and the slice
iterated against all session. The +16% overfitting gap against vfc-js is why
contributor-scan Req 8.1/8.2 exist.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG

tests/test_cpg_backend.py

@@ -44,8 +44,21 @@ def test_the_seam_imports_nothing_outside_the_standard_library() -> None:
             imported.add(node.module.split(".")[0])
         elif isinstance(node, ast.Import):
             imported.update(alias.name.split(".")[0] for alias in node.names)
-    stdlib = {"__future__", "json", "os", "re", "shutil", "subprocess", "tempfile", "dataclasses", "pathlib", "typing",
-              "collections", "logging", "hashlib"}
+    stdlib = {
+        "__future__",
+        "json",
+        "os",
+        "re",
+        "shutil",
+        "subprocess",
+        "tempfile",
+        "dataclasses",
+        "pathlib",
+        "typing",
+        "collections",
+        "logging",
+        "hashlib",
+    }
     assert imported <= stdlib, f"the seam imports outside the standard library: {sorted(imported - stdlib)}"
     assert "import jpype" not in source and "py4j" not in source, "Joern is reached by subprocess, never in-process"