Add formal conformance suite for AWF config source contract and DriftRecord invariants

[Copilot]

This issue formalizes the AWF config source-of-truth contract in specs/awf-config-sources-spec.md and requires executable coverage for CR-01 through CR-06a plus DriftRecord schema constraints. This PR adds a dedicated formal test suite that encodes those predicates as deterministic checks.

• Formal coverage for CR-01..CR-06a

  • Added /pkg/awfconfig/awfconfig_formal_test.go with conformance tests for:
    • dual-source consultation (spec + schema)
    • drift trigger conditions (schema change, schedule, explicit request)
    • corrective PR requirements for actionable drift categories
    • SLA window computation in business days
    • escalation requirement and owner assignment

• DriftRecord schema invariants

  • Added typed DriftRecord test model and predicate checks for:
    • required fields non-empty
    • category enum exhaustiveness (missing_in_ghaw|missing_in_schema|spec_mismatch)
    • property path dot-notation validity
    • serialized record rejecting additional properties

• Safeguard and coverage predicates

  • Added explicit checks for degraded-mode behavior when canonical sources are unavailable.
  • Added schema-property coverage predicate asserting all schema properties are represented in gh-aw references.

type DriftRecord struct {
    PropertyPath    string `json:"property_path"`
    DriftCategory   string `json:"drift_category"`
    SuggestedAction string `json:"suggested_action"`
    DetectedAt      string `json:"detected_at"`
}

func TestDriftRecordNoExtraFields(t *testing.T) {
    extra := []byte(`{"property_path":"apiProxy.anthropicAutoCache","drift_category":"missing_in_ghaw","suggested_action":"Add coverage","detected_at":"2026-07-27T16:00:00Z","extra":true}`)
    assert.False(t, hasNoAdditionalProperties(extra))
}

• Fixes [formal-spec] awf-config-sources-spec.md — Formal model & test suite — 2026-07-27 #48402

[pelikhan]

@copilot resolve the merge conflicts on this branch.

[Copilot]

Pull request overview

Adds a test-only AWF configuration conformance model covering drift records, SLA handling, escalation, safeguards, and schema coverage.

Changes:

• Adds formal predicate tests under pkg/awfconfig.
• Updates generated model-cost metadata for the Copilot smoke workflow.

Show a summary per file

File	Description
pkg/awfconfig/awfconfig_formal_test.go	Adds AWF contract models and conformance tests.
.github/workflows/smoke-copilot-auto.lock.yml	Adds generated pricing metadata for the auto model.

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• Files reviewed: 2/2 changed files
• Comments generated: 6
• Review effort level: Medium