test(config-audit): add baseline-all-a fixture + grade-stability regression test

plugins/config-audit/tests/fixtures/baseline-all-a/.claude/rules/typescript.md

@@ -0,0 +1,13 @@
+---
+paths: src/**/*.ts
+---
+
+# TypeScript Rules
+
+Use strict TypeScript throughout.
+
+## Mandatory
+
+- `strict: true` in tsconfig
+- No `any` — prefer `unknown` at boundaries
+- Prefer `type` aliases for simple shapes, `interface` for extendable objects