test(config-audit): add Opus 4.7 pattern fixtures (cache, redundant, imports, sonnet-era)

tests/fixtures/opus-47/deep-imports/layer2.md

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+# Layer 2
+
+Second layer of the chain. This file is imported by layer1.md and imports
+layer3.md in turn, forming a 3-deep @import chain that the TOK scanner
+should flag.
+
+## Architecture Notes
+
+The ficticious project uses a layered architecture split across:
+
+- Application layer (HTTP adapters, CLI adapters)
+- Domain layer (pure business logic)
+- Infrastructure layer (databases, caches, external APIs)
+
+## Dependency Rules
+
+- Application depends on domain but not infrastructure.
+- Infrastructure implements ports defined in the domain.
+- Domain never imports from application or infrastructure.
+- Cross-cutting concerns (logging, tracing) live as ports.
+
+## Observability
+
+- Structured logs with correlation ids.
+- Metrics scraped from a `/metrics` endpoint.
+- Trace spans around domain service boundaries.
+- Health checks separate from metrics endpoints.
+
+## Data Access
+
+- Repositories return domain objects, never ORM entities.
+- Database migrations numbered sequentially.
+- Idempotent migrations where feasible.
+- Readonly replicas for analytical queries.
+
+## Caching
+
+- Read-through cache for hot entities.
+- TTL chosen per entity class.
+- Invalidate on write, not on read miss.
+- Measure hit-rate per cache bucket.
+
+@layer3.md