fix(ci): raise the build heap cap from 3072 to 4096 MB (#11781)

main alone peaks at ~3.14 GB RSS building packages/cli under the 3072 MB
--max-old-space-size cap, so whether tsc --build survives is decided by
runner load: under CPU contention GC throughput drops and the build dies
with 'Ineffective mark-compacts near heap limit'. Three OOM failures on
three distinct runners versus green builds of the identical commit on
quieter ones were observed on a single PR head.

4096 gives ~30% headroom over the measured footprint; worst-case RSS
(~4.3 GB) stays safe on GitHub-hosted 16 GB runners and the ECS fleet.
The test lanes keep 3072 — per-package vitest heaps are far smaller and
have no OOM evidence.

Fixes #11780

package.json

@@ -38,7 +38,7 @@
     "debug": "cross-env DEBUG=1 node --inspect-brk scripts/start.js",
     "generate": "node scripts/generate-git-commit-info.js",
     "generate:settings-schema": "node --import tsx/esm scripts/generate-settings-schema.ts",
-    "build": "cross-env NODE_OPTIONS=\"--max-old-space-size=3072\" node scripts/build.js",
+    "build": "cross-env NODE_OPTIONS=\"--max-old-space-size=4096\" node scripts/build.js",
     "build-and-start": "npm run build && npm run start",
     "build:vscode": "node scripts/build_vscode_companion.js",
     "build:all": "npm run build && npm run build:sandbox && npm run build:vscode",