merge: resolve conflicts with upstream main (firecrawl + exa_search)

ensureConfigFile(): keep our refactored version that delegates to
buildNewProjectConfig({}) instead of upstream's duplicated logic.

buildNewProjectConfig(): add firecrawl and exa_search API key
detection alongside existing brave_search, matching upstream's
new integrations.

package-lock.json

@@ -16,7 +16,7 @@
         "esbuild": "^0.24.0"
       },
       "engines": {
-        "node": ">=16.7.0"
+        "node": ">=20.0.0"
       }
     },
     "node_modules/@bcoe/v8-coverage": {