fix(b-gate): the binding measures an execution, and the row-3 sentence stops counting doors

Third repair of the same failure, and the first that does not read a NAME. The judge measured
row 1 to 17 of 17 with 17 one-line probes and a door module without a single import: "the probe
touches the door" was still a text check, one notch further in.

What is measured now, in the probe's own source: an EXECUTION SITE (a process starter carrying
the door's name in its arguments, or the entry imported from the door's module and called), and
an assert that is DATA-DEPENDENT on that call. Dead code is pruned first -- a call in a branch
that never runs, or after a return, is no execution. The honest forms the suite already uses
keep counting: the command built in a variable first, and the subprocess started in a helper
that returns it.

All seven forms the judge measured (a1, a2, b1, b2, c1, c2 + the one-liner recipe) now give
0 of 1, each with an rc-0 control in the same setup.

[mutation-ok] -- no guard is switched off. The two `if False:` lines in this diff are the
judge's b1 probe form planted as test DATA (a Python string written into a tmp_path file the
gate only PARSES, never runs) and the docstring naming why dead code is pruned. The commit adds
the rule that makes `if False:` around a door call stop counting.

Naming the step becomes a DISCRIMINATOR, as a class: it is required only when more than one step
stands behind the same door. Driving a door with a sole step IS driving that step -- which is why
`gate` (a real end-to-end door probe against v1_gate) was rejected on a name technicality. Row 1:
0 -> 1 of 17. For a subcommand door the command name must stand in what was actually executed,
and the CLI itself must be registered or `-m`-runnable: an add_parser in a module nobody can
start is no door.

held_out: a reason must be named prose. "-", "todo", "x", "." were all accepted as a reason by
`.strip()`; measured against the contract's own 28 reasons (shortest: 30 chars, three words).

Row 3: the five forms the checkpoint measured as open AND cheap to close are closed -- importlib
for both SDK names, deno/npm exec/yarn dlx, and the official TypeScript SDK. 12 of 12 -> 15 of 15,
still 0 hits over 512 published files. The limit sentence stops enumerating what remains ("EXACTLY
TWO", then "THREE" -- both falsified by the first new measurement) and says what the guard IS.

N7 stays open in the gate and is closed in the suite: a deleted off-path step still shrinks the
denominator silently there, so the four are written out in an arm that goes red when one goes.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/portfolio_optimiser/evals/b_gate.json

@@ -520,6 +520,27 @@
         "pattern_b64": "X19pbXBvcnRfX1woXHMqWyInXShjbGF1ZGVfYWdlbnRfc2RrfGNsYXVkZV9jb2RlX3Nka3xhbnRocm9waWMpWyInXQ==",
         "known_positive_b64": "X19pbXBvcnRfXygiY2xhdWRlX2FnZW50X3NkayIp",
         "known_negative_b64": "X19pbXBvcnRfXygiYWdlbnRfZnJhbWV3b3JrIik="
+      },
+      {
+        "id": "dynamisk-import-modul",
+        "label": "importlib mot en Claude-klient",
+        "pattern_b64": "aW1wb3J0bGliXC5pbXBvcnRfbW9kdWxlXChccypbIlwnXShjbGF1ZGVfYWdlbnRfc2RrfGNsYXVkZV9jb2RlX3Nka3xhbnRocm9waWMpWyJcJ10=",
+        "known_positive_b64": "aW1wb3J0bGliLmltcG9ydF9tb2R1bGUoImNsYXVkZV9hZ2VudF9zZGsiKQ==",
+        "known_negative_b64": "aW1wb3J0bGliLmltcG9ydF9tb2R1bGUoImFnZW50X2ZyYW1ld29yayIp"
+      },
+      {
+        "id": "node-runner-indirekte",
+        "label": "claude-code startet av deno, npm exec, yarn dlx eller pnpm exec",
+        "pattern_b64": "KGRlbm9ccytydW5cYlteXG5dKj9ucG06fG5wbVxzK2V4ZWNcYlteXG5dKj98eWFyblxzK2RseFxiW15cbl0qP3xwbnBtXHMrZXhlY1xiW15cbl0qPykoQGFudGhyb3BpYy1haS8pP2NsYXVkZS1jb2RlXGI=",
+        "known_positive_b64": "ZGVubyBydW4gLUEgbnBtOkBhbnRocm9waWMtYWkvY2xhdWRlLWNvZGUgLXAgIngi",
+        "known_negative_b64": "bnBtIGV4ZWMgcHJldHRpZXIgLS0gLS13cml0ZSAu"
+      },
+      {
+        "id": "sdk-ts-import",
+        "label": "import av den offisielle TypeScript-SDK-en",
+        "pattern_b64": "KGltcG9ydHxyZXF1aXJlKVxiW15cbl0qWyJcJ11AYW50aHJvcGljLWFpLyhjbGF1ZGUtYWdlbnQtc2RrfGNsYXVkZS1jb2RlLXNka3xjbGF1ZGUtY29kZSlbIlwnXQ==",
+        "known_positive_b64": "aW1wb3J0IHsgcXVlcnkgfSBmcm9tICJAYW50aHJvcGljLWFpL2NsYXVkZS1hZ2VudC1zZGsiOw==",
+        "known_negative_b64": "aW1wb3J0IHsgeiB9IGZyb20gInpvZCI7"
       }
     ]
   },