feat(models): bridge Chat Completions and Responses through Claude runtime

package.json

@@ -8,6 +8,7 @@
   "scripts": {
     "test": "npm run test:core",
     "test:core": "npm run typecheck && npm run test:chat && npm run test:sessions && npm run test:persistence && npm run test:conversation",
+    "test:model-bridge": "esbuild scripts/protocol-bridge-regression.ts --bundle --platform=node --format=esm --outfile=.tmp/protocol-bridge-regression.mjs --log-level=warning && node .tmp/protocol-bridge-regression.mjs && node scripts/claude-bridge-host-regression.mjs",
     "test:alignment": "node scripts/run-alignment-regression.mjs",
     "test:alignment:dom": "node scripts/run-alignment-regression.mjs --require-dom",
     "test:image-lifecycle": "node scripts/test-image-lifecycle.mjs",