feat(core-eslint): workspace helper for conformance rules

packages/core-eslint/rules/_workspace.js

@@ -0,0 +1,28 @@
+import fs from "node:fs";
+import path from "node:path";
+
+/**
+ * Reads the `packages:` list from `pnpm-workspace.yaml` at the given repo
+ * root. Returns an array of package glob strings (e.g. ["apps/*", "packages/*"]).
+ * Returns [] when the file is missing or has no `packages:` key.
+ *
+ * Uses regex extraction over YAML parsing to avoid a `js-yaml` dependency;
+ * the `packages:` block in pnpm-workspace.yaml has a stable, well-known
+ * shape and this approach is sufficient.
+ */
+export function readWorkspacePackages(repoRoot) {
+  const yamlPath = path.join(repoRoot, "pnpm-workspace.yaml");
+  let src;
+  try {
+    src = fs.readFileSync(yamlPath, "utf8");
+  } catch {
+    return [];
+  }
+  const blockMatch = src.match(/^packages:\s*\n((?:\s+-\s+.+\n?)+)/m);
+  if (!blockMatch) return [];
+  return blockMatch[1]
+    .split("\n")
+    .map((line) => line.match(/^\s+-\s+"?([^"]+?)"?\s*$/))
+    .filter((m) => m !== null)
+    .map((m) => m[1]);
+}