fix scorecard verdict when sealed-generation census is invalid

[ScriptedAlchemy]

Defect

efficiency-scorecard can report a successful run and overall ok verdict when the run's cold-index graph census is explicitly unavailable because the sealed generation census is invalid.

Confirmed artifact:

• target/efficiency-scorecard-20260902T093325Z-final-certification/scorecard.json
• source commit: 5749e4fcfe268e17bd19a0e6ef90c646f7b37289
• run 3: cold_index.graph_statistics = { \"state\": \"unavailable\", \"reason\": \"sealed_generation_census_invalid\" }
• the same run still has status: \"ok\"
• the top-level scorecard still has verdict: \"ok\"

Defect location

scripts/efficiency-scorecard.py:1058-1070 derives the overall verdict and exit code only from run[\"status\"] != \"ok\". The cold-index census state never contributes to run status, overall verdict, or process exit status.

Required behavior

A run with cold_index.graph_statistics.state != \"observed\" due to sealed_generation_census_invalid must not report status: \"ok\"; consequently the scorecard verdict must not be ok and the command must exit non-zero. Add a regression fixture covering this exact contradictory shape.

[ScriptedAlchemy]

Duplicate of #797. The shared defect is fixed on PR #707 branch by commit 83f3ac9f0; #797 tracks the fix through merge.

[ScriptedAlchemy]

Canonical issue note: #796 and #797 were exact duplicate filings and are now closed in favor of this issue. The scorecard verdict fix remains actively in progress; this issue stays open until its regression test and corrected verdict behavior are landed and verified.