test(config-audit): add marketplace-small/medium/large scanner fixtures

plugins/config-audit/tests/fixtures/marketplace-medium/CLAUDE.md

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+# Marketplace Medium
+
+Marketplace with 3–4 plugins, modest hooks.json, single MCP server, and
+one @import to a shared configuration file.
+
+## Plugins
+
+- plugin-alpha — linting
+- plugin-beta — formatting
+- plugin-gamma — test runner
+- plugin-delta — release automation
+
+## Commands
+
+- `npm run build`
+- `npm test`
+- `npm run lint`
+- `npm run format`
+
+## Conventions
+
+Standard TypeScript project layout. Shared patterns imported below.
+
+@.claude/shared.md