test(pipeline): the checks of the pure pipeline

Stream, Normalize, Merge, Dispositions, Config, CodeKeys and the pure half
of CommitsMode, each a test of its own (131 checks). The fixture rewrites
are checked in (code-keys/<name>/, commits3/), so the suite reads fixtures
and edits nothing. The allowlist, command-line and MCP checks of
CommitsMode come with the pool they test.

Among them: this binary's `<exe> sql` spelling counts as a SQL call, and a
result line with a raw U+2028 in a JSON string is still the result line.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/Goldens/fixture/commits3/0003-add-tests.patch

@@ -0,0 +1,24 @@
+From 3333333333333333333333333333333333333333 Mon Sep 17 00:00:00 2001
+From: Jorijn van der Graaf <jorijnvdgraaf@catcrafts.net>
+Date: Wed, 24 Sep 2026 10:10:00 +0200
+Subject: [PATCH 3/3] add tests
+
+Tests for greet.
+---
+ tests/test_hello.py | 3 +++
+ 1 file changed, 3 insertions(+)
+ create mode 100644 tests/test_hello.py
+
+diff --git a/tests/test_hello.py b/tests/test_hello.py
+new file mode 100644
+index 0000000..1111111
+--- /dev/null
++++ b/tests/test_hello.py
+@@ -0,0 +1,3 @@
++from hello import greet
++def test_greet():
++    assert greet("x") == "hello x"
+
+base-commit: 0000000000000000000000000000000000000000
+-- 
+2.51.0