chore: add e2e convenience tooling (cloud-e2e, e2e-monitor)

[svidgen]

Summary

Adds e2e test management tooling to amplify-codegen, bringing it in line with amplify-cli and amplify-category-api.

What's Added

Scripts

• scripts/e2e-test-manager.ts — TypeScript-based e2e management tool with commands:

  • status — Show batch build status
  • monitor — Poll with auto-retry of transient failures (5-min intervals)
  • retry — Retry failed builds
  • list — List recent build batches
  • failed — Show failed builds with log commands
  • logs — View CloudWatch logs for a specific build

• scripts/cloud-e2e.sh — Standalone script to trigger e2e batch builds (supports pr/<number> argument)

Yarn Scripts

yarn e2e-status <batchId>
yarn e2e-monitor <batchId> [maxRetries]
yarn e2e-retry <batchId>
yarn e2e-list [limit]
yarn e2e-failed <batchId>
yarn e2e-logs <buildId>

Documentation

• AGENTS.md — Comprehensive guide for running and monitoring e2e tests
• Updated scripts/sample.env with setup documentation

Design

Modeled after amplify-cli's e2e-test-manager.ts pattern. Uses the existing @aws-sdk/client-codebuild dependency and AmplifyAPIE2EProd profile convention from cloud-utils.sh.

No account IDs or secrets in committed files — all sensitive values come from scripts/.env (gitignored).

Testing

• TypeScript compilation verified (tsc --noEmit)
• No secrets or account IDs in committed files (grep verified)