fix: use absolute package path for node-stream-helpers require in app-page template
The relative require('../../server/stream-utils/node-stream-helpers') fails
with webpack because app-page.ts is a virtual entry resolved from the project
root, not the template's file location. Use require('next/dist/...') instead.
Also update AGENTS.md and pr-status skill with CI repro best practices:
always match exact CI env vars (IS_WEBPACK_TEST, feature flags) and never
use NEXT_SKIP_ISOLATE when verifying module resolution fixes.