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>

src/portfolio_optimiser/mandate.py

@@ -334,7 +334,9 @@ class ApproachOutcome:
 
     id: str
     label: str
-    status: Literal["validated", "rejected", "not_evaluated"]
+    #: ``unsupported`` (row 6): the numbers held but the approach declared no binding requirement,
+    #: so it is neither a success nor a numeric rejection. Never counted as validated.
+    status: Literal["validated", "rejected", "unsupported", "not_evaluated"]
     detail: str = ""
     saving_nok: float | None = None
 
@@ -471,6 +473,8 @@ def settle(
             lines.append(f"  {row.id:<20} VALIDATED     {amount:>14}   {row.label}")
         elif row.status == "rejected":
             lines.append(f"  {row.id:<20} REJECTED      {row.detail}")
+        elif row.status == "unsupported":
+            lines.append(f"  {row.id:<20} UNSUPPORTED   {row.detail}")
         else:
             lines.append(f"  {row.id:<20} NOT EVALUATED {row.detail}")