Tighten page-refresh prechecks and incomplete-evidence guidance

[sergeliatko]

Summary

• Closes Tighten page-refresh prechecks and incomplete-evidence guidance #14.
• Publishes the v0.4.1 candidate with catalog 0.4.1 and page-refresh-brief@2.0.1.
• Reorders the stable page-refresh steps so the blocking target precheck precedes result inspection while retaining the maximum of three representative queries.
• Distinguishes readiness failure, execution-time required-evidence failure, and successful completed-empty evidence without changing any result-contract version.
• Requires automated score conclusions to be checked against underlying and independently observed evidence.

Contract and fixture evidence

• Adds three registered behavior scenarios for target precheck order, structurally unavailable required evidence, and score conflicts.
• Adds one dedicated contract-valid seo-diagnostic/v1 fixture for execution-time required-evidence failure.
• Keeps the four result-contract identifiers and their schemas unchanged.
• Adds no provider binding, runtime mapping, current price, persistent execution behavior, or finished content-writing behavior.

Verification

• npm run validate: passed with 6 recipes, 4 result contracts, 34 contract fixtures, and 31 registered evaluation cases across 12 segments.
• Fresh-context blocking-target-precheck: passed all 3 named invariants.
• Fresh-context execution-time-evidence-failure: passed all 5 named invariants, including structural validity and omitted handoff.
• Fresh-context automated-score-evidence-input: passed all 3 named invariants.
• Fresh-context preserved-boundary regression: passed all 7 public-source checks; zero-charge settlement remains a connected-runtime verification responsibility.
• npm run package -- v0.4.1: passed.
• npm run release:verify-assets -- v0.4.1: passed across two byte-identical builds.
• npm run release:preflight -- v0.4.1: passed on frozen tree digest aa67613feb88aed235df5fb9483ae25e9e9f5c7c79c8adf334e7abcaf970d4fa.
• Generated SHA256SUMS digest: c5de653d370a17b4931c6ce4229ba775232c2b91ef0a44609aac4c8b9861facc.

The deterministic validation command registered the behavioral cases but did not execute them; the fresh-context results above are the separate behavioral evidence.