refactor(scripts): share guard runners and paged select UI

scripts/lib/pairing-guard-context.mjs

@@ -0,0 +1,13 @@
+import path from "node:path";
+import { resolveRepoRoot, resolveSourceRoots } from "./ts-guard-utils.mjs";
+
+export function createPairingGuardContext(importMetaUrl) {
+  const repoRoot = resolveRepoRoot(importMetaUrl);
+  const sourceRoots = resolveSourceRoots(repoRoot, ["src", "extensions"]);
+  return {
+    repoRoot,
+    sourceRoots,
+    resolveFromRepo: (relativePath) =>
+      path.join(repoRoot, ...relativePath.split("/").filter(Boolean)),
+  };
+}