test(grey-state): add proptests for transition validation and judgments

[wangzishuai1987]

Summary

Adds property-based tests for the block state transition module (Section 4):

validate_header:

• Rejects blocks with timeslot ≤ state timeslot (non-advancing)
• Accepts blocks with advancing timeslot and valid author index

apply_judgments (Section 10):

• Supermajority positive votes → report marked "good"
• Zero positive votes → report marked "bad"
• Minority positive votes (1 to one-third) → report marked "wonky"
• Multiple verdicts on different reports are handled independently

rotate_auth_pool:

• Clears the pool on epoch boundaries

Refs: #229

[github-actions]

Genesis Review

Comparison targets:

• 72e0c9d8 (72e0c9d)
• f271ebaf (f271eba)
• 2fe26593 (2fe2659)
• f334ec72 (f334ec7)
• 5a3d08fa (5a3d08f)
• 011549cd (011549c)
• 893afee6 (893afee)

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/review
difficulty: <commit1>, <commit2>, ..., <commitN>, currentPR
novelty: <commit1>, <commit2>, ..., <commitN>, currentPR
design: <commit1>, <commit2>, ..., <commitN>, currentPR
verdict: merge

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[johandroid]

/review
difficulty: 72e0c9d, f271eba, 2fe2659, currentPR, f334ec7, 011549c, 893afee, 5a3d08f
novelty: 72e0c9d, f271eba, 2fe2659, currentPR, f334ec7, 5a3d08f, 011549c, 893afee
design: 72e0c9d, f271eba, 2fe2659, f334ec7, 011549c, 893afee, 5a3d08f, currentPR
verdict: notMerge

The transition proptest coverage is a good target area, but this patch appears not to compile against the current API: State has no Default implementation, and rotate_auth_pool takes (&mut State, &GuaranteesExtrinsic, &Config), not a boolean. Even aside from compilation, the “valid author index” header test uses a minimal state without constructing validators. Ranked high enough for attempting meaningful state-transition coverage, but design is last until the tests are wired to real fixtures.

[github-actions]

JAR Bot: Review recorded from @johandroid (1 reviews, 0 meta-reviews).
Merge weight: 0/37665 (need >50%).