feat(FN-3470): prefer source aliases for runtime plugins and add test artif

Merges FN-3470 in two steps: first, runtime plugins now prefer source path aliases over build artifacts, with hardening tests for vitest alias resolution and plugin view registry updates; second, a new `ensure-test-artifacts.mjs` bootstrap script guarantees required test files exist before test runs

Fusion-Task-Id: FN-3470

scripts/__tests__/ensure-test-artifacts.test.mjs

@@ -0,0 +1,33 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { detectMissingArtifacts, ensureTestArtifacts } from "../ensure-test-artifacts.mjs";
+
+test("detectMissingArtifacts returns missing package list", () => {
+  const missing = detectMissingArtifacts("/repo", () => false);
+  assert.ok(missing.length >= 5);
+  assert.equal(missing[0].name, "@fusion/core");
+});
+
+test("ensureTestArtifacts skips build when nothing is missing", () => {
+  let called = false;
+  const built = ensureTestArtifacts("/repo", () => {
+    called = true;
+  }, () => true);
+
+  assert.equal(called, false);
+  assert.deepEqual(built, []);
+});
+
+test("ensureTestArtifacts builds only missing packages", () => {
+  const calls = [];
+  const built = ensureTestArtifacts(
+    "/repo",
+    (cmd, args, cwd) => calls.push({ cmd, args, cwd }),
+    (fullPath) => !fullPath.includes("fusion-plugin-openclaw-runtime"),
+  );
+
+  assert.deepEqual(built, ["@fusion-plugin-examples/openclaw-runtime"]);
+  assert.equal(calls.length, 1);
+  assert.equal(calls[0].cmd, "pnpm");
+  assert.deepEqual(calls[0].args, ["--filter", "@fusion-plugin-examples/openclaw-runtime", "build"]);
+});