docs: clarify integration vs e2e test boundaries and add e2e README

[jariy17]

Summary

• Rewrites integ-tests/README.md — the old README described e2e behavior (AWS credentials, CloudFormation stacks, real resource costs) when the actual tests do none of that. Now correctly describes what integration tests do: run the CLI locally, assert on agentcore.json and stdout, no AWS required.
• Adds e2e-tests/README.md — new README documenting the AWS boundary, prerequisites, the createE2ESuite() factory pattern, key test patterns, file naming conventions, and cleanup requirements.
• Updates docs/TESTING.md — adds an E2E Tests section with a link to the new README, fixes the stale integration tests section that incorrectly listed AWS credentials as a prerequisite.

Test plan

• Verify integ-tests/README.md no longer mentions AWS credentials, CloudFormation, or costs
• Verify e2e-tests/README.md exists and accurately describes the e2e pattern
• Verify docs/TESTING.md links to both READMEs and the integration tests section no longer says AWS credentials are required

[agentcore-cli-automation]

Reviewed — docs-only PR. Spot-checked the claims against the repo:

• e2e-tests/e2e-helper.ts exports createE2ESuite, teardownE2EProject, writeAwsTargets, runAgentCoreCLI, cleanupStaleCredentialProviders, baseCanRun, and hasAws ✅
• src/test-utils/index.ts exports createTestProject, runCLI, readProjectConfig, and TestProject — matches the integ-tests example imports ✅
• createTestProject({ noAgent: true }) is a real option ✅
• npm run test:e2e and npm run test:integ scripts both exist in package.json ✅
• Integ-tests contain no references to AWS credentials / STS / profiles, so the "no AWS required" claim is accurate ✅
• The lifecycle description for createE2ESuite() (create → deploy → invoke → status → logs → traces → destroy) matches the actual it.skipIf blocks in the helper ✅

No serious issues — LGTM.

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	42.89%	8936 / 20830
🔵	Statements	42.17%	9485 / 22491
🔵	Functions	39.66%	1537 / 3875
🔵	Branches	39.82%	5769 / 14486

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