Add semantic-drift signals and a deterministic drift-evaluator for confidence decay

[danielbdyer]

Motivation

• Surface runtime semantic-consistency signals (label/role mismatch, accessible-name semantics change, unexpected transition effects, assertion-target ambiguity) so the system can distinguish semantic drift from locator degradation.
• Use deterministic decay rules to reduce derived overlay confidence when run evidence indicates real drift, and expose operator controls to tune decay behavior per artifact class.

Description

• Extended StepExecutionReceipt to include semanticConsistency signals and populated them during runtime step execution in lib/runtime/scenario.ts.\
• Added lib/application/drift-evaluator.ts which ingests run records and produces deterministic decay evaluations (total decay, floor, suppression counts, applied-signal rationale).\
• Integrated decay into the confidence overlay projection in lib/application/confidence.ts so overlay score is reduced by the computed decay and decay lineage is recorded in ArtifactConfidenceRecord.lineage.decay.\
• Added trust-policy config/schema surfaces (confidenceDecay) to tune per-artifact decay rates, minimumFloor, and suppressionWindowRuns, and updated the default .tesseract/policy/trust-policy.yaml.\
• Treated semantic drift as a first-class operator concern by adding semantic-drift inbox kind, a semantic-drift hotspot kind, and scorecard fields (semanticDriftHotspotCount, runtimeFailureClasses) to surface actionable groupings and distinct failure classes.
• Updated schemas, types, validators, and a few test fixtures to reflect the new fields and kinds.

Testing

• Ran targeted test suite: npm test -- tests/domain-validation-lanes.spec.ts tests/hotspots.spec.ts tests/vscode-integration.laws.spec.ts, all tests passed (24 passed).\
• Ran npm run types / npm run build; npm run build failed due to pre-existing unrelated TypeScript issues in lib/application/replay-interpretation.ts and lib/infrastructure/mcp/dashboard-mcp-server.ts not introduced by this change (noted during validation).

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Codex Task