perf: lazy-load editor runtime

Issue: #337
User-Visible: yes

scripts/bundle-budget.mjs

@@ -0,0 +1,39 @@
+#!/usr/bin/env node
+import { readFileSync } from 'node:fs';
+import { resolve } from 'node:path';
+import { pathToFileURL } from 'node:url';
+
+export const INITIAL_VIEW_GZIP_BUDGET = 256_000;
+
+export function assertBundleBudget(manifest, budget = INITIAL_VIEW_GZIP_BUDGET) {
+  if (manifest?.schema !== 1 || !Array.isArray(manifest.files)) {
+    throw new Error('invalid houseplan-assets.json');
+  }
+  if (!manifest.lazyEditorFiles?.length) {
+    throw new Error('bundle has no lazy editor graph');
+  }
+  if (manifest.initialViewFiles.some((path) => manifest.lazyEditorFiles.includes(path))) {
+    throw new Error('initial View graph overlaps lazy editor graph');
+  }
+  if (manifest.initialViewGzipBytes > budget) {
+    throw new Error(
+      `initial View graph ${manifest.initialViewGzipBytes} B gzip exceeds ${budget} B budget`,
+    );
+  }
+  return {
+    initialViewGzipBytes: manifest.initialViewGzipBytes,
+    lazyEditorGzipBytes: manifest.lazyEditorGzipBytes,
+  };
+}
+
+if (import.meta.url === pathToFileURL(process.argv[1] || '').href) {
+  try {
+    const manifest = JSON.parse(readFileSync(resolve('dist/houseplan-assets.json'), 'utf8'));
+    const result = assertBundleBudget(manifest);
+    console.log(`initial View: ${result.initialViewGzipBytes} B gzip`);
+    console.log(`lazy editor: ${result.lazyEditorGzipBytes} B gzip`);
+  } catch (error) {
+    console.error(error instanceof Error ? error.message : String(error));
+    process.exit(1);
+  }
+}