Ask a foreign manifest whether it can be loaded, not how it was wired

The performance harness runs the candidate's benchmark against a
baseline checkout, so the candidate's validator reads a manifest built
by an older commit. #535 put a rule about the CURRENT build into that
shared validator — the panel graph must not contain the card facade —
and it is false of every build before #535 by construction. The
candidate then refused to load any older baseline: all nine performance
profiles went red at once on the same step, the stable release gate
withheld `houseplan-card.js` from the published v1.75.0, and none of it
was about speed.

assertBundleManifest now answers only the loader's question: paths
exist, nothing is duplicated, graphs reference listed assets, sizes add
up. The topology of the current build moves to assertOwnBundleTopology,
called from bundle-sync.mjs, which materializes our own dist, and from
the unit test that reads dist/houseplan-assets.json. Neither ever looks
at a foreign tree.

Reproduced end to end, not only in a unit: a v1.74.0 worktree built with
its own code, then `node demo/benchmark_large_house.mjs
--target-root=<baseline>` from this tree. Before the change it stops
with «initial panel graph must contain its own stable entry only»; after
it, the profile is captured.

Issue: #537
User-Visible: no

scripts/bundle-sync.mjs

@@ -16,7 +16,7 @@ import {
 import { dirname, relative, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import {
-  assertBundleManifest, orderedBundlePayload, verifyBundleTree,
+  assertBundleManifest, assertOwnBundleTopology, orderedBundlePayload, verifyBundleTree,
 } from './bundle-tree.mjs';
 
 const ROOT = resolve(dirname(fileURLToPath(import.meta.url)), '..');
@@ -38,6 +38,9 @@ const parseManifest = (path) => {
   return parsed;
 };
 const sourceManifest = assertBundleManifest(parseManifest(manifestPath), manifestPath);
+// #537: this script materializes OUR dist, so the topology of the current
+// build is judged here and nowhere in the shared loader-side validator.
+assertOwnBundleTopology(sourceManifest, manifestPath);
 const managedFiles = [MANIFEST_NAME, ...sourceManifest.files.map((file) => file.path)];
 const sha256 = (path) => createHash('sha256').update(readFileSync(path)).digest('hex');
 const contained = (root, name) => {