feat(row6): a proposal whose approach declared no requirement is unsupported

Stress round 6 validated three falsification arms, and every validated
approach rested only on run-level declarations nobody can attribute to one
approach. declare_requirement now takes a required approach_id (a mandate
id or own-proposal; an unknown id is refused naming the valid ones), and a
ValidatedProposal whose approach has neither a mandate requirement nor a
declaration under its own id becomes validator.Unsupported - a Rejection
subclass carrying the validator's own ruling, reported as `unsupported` in
coverage, the outcome artefact, the settlement and the judge, and never
counted or summed. The rule is active whenever the debate held the
declaration tool, the micro base included; the road and pre-pass paths are
untouched. Declaration quality is not judged, so the rule can be satisfied
by declaring any document the run read.

The v1 gate's row 6 probes pass; its artefact half reads IKKE MÅLT because
stress round 6 predates approach-addressed declarations, and IKKE MÅLT is
never green - it fails the exit code.

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

tests/test_trace_and_coverage_loadbearing.py

@@ -355,7 +355,7 @@ async def test_a_commissioned_run_writes_the_coverage_artefact(tmp_path: Path) -
     payload = json.loads((out / "r1-coverage.json").read_text(encoding="utf-8"))
     assert payload["stop_reason"] == "", "nothing cut this run short"
     assert [r["id"] for r in payload["rows"]] == ["a1"]
-    assert payload["rows"][0]["status"] in {"validated", "rejected"}
+    assert payload["rows"][0]["status"] in {"validated", "rejected", "unsupported"}
 
 
 async def test_a_mandateless_run_leaves_the_outbox_byte_identical(tmp_path: Path) -> None: