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

plugins/config-audit/tests/fixtures/opus-47/cache-breaking/CLAUDE.md

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+# Cache-Breaking Volatile Top
+
+> Last Run: {timestamp} — volatile placeholder that changes on every invocation
+> Session: {uuid} — another volatile field
+> Now: {date}
+
+## Recent Activity
+
+- 2026-04-19T12:00:00Z — User A edited file X
+- 2026-04-19T11:45:00Z — User B pushed commit Y
+- 2026-04-19T11:30:00Z — CI run Z completed
+- 2026-04-19T11:15:00Z — Review comment added
+- 2026-04-19T11:00:00Z — Deployment triggered
+- 2026-04-19T10:45:00Z — Log rotation ran
+- 2026-04-19T10:30:00Z — Backup verified
+- 2026-04-19T10:15:00Z — Cache cleared
+- 2026-04-19T10:00:00Z — Session started
+
+## Current State
+
+The status widget above renews on every turn, pushing the stable-prefix
+content further down the file. Under Opus 4.7 prompt caching, any change
+within the first block invalidates the cache-prefix, forcing a full
+recomputation each turn and inflating token cost per session.
+
+## Stable Content (cache target)
+
+Below this line is content that rarely changes — the project overview,
+conventions, and shared rules. But because the volatile header sits ABOVE
+this stable section, it cannot benefit from caching.
+
+## Project Overview
+
+A fixture designed to trip the Opus 4.7 TOK scanner's cache-breaking
+detector (CA-TOK-001). The first 30 lines contain volatile-looking
+patterns (timestamps, session ids, running activity logs) that would
+break prompt-cache reuse on every turn.
+
+## Commands
+
+- `npm run build`
+- `npm test`
+
+## Conventions
+
+- Conventional Commits
+- TypeScript strict