Add AWS skill: IAM, serverless patterns, service guidelines & CDK conventions

[a7medsa22]

Summary

Adds config/skills/aws.md — a concise, actionable AWS skill for AI-Nexus:
IAM least-privilege essentials + policy testing
-Lambda/serverless patterns with handler example

• CloudFormation/CDK conventions + parameterization tips
• Anti-patterns checklist to avoid common mistakes
• PR review checklist + semantic router prompts

Closes #3

Type

• New rule (config/rules/, config/commands/, config/skills/, etc.)
• Rule improvement (existing rule)
• CLI feature / fix (src/)
• Bug fix
• Documentation

Changes

• config/skills/aws.md
  • Adds config/skills/aws.md — a concise, actionable AWS skill for AI-Nexus:

Why

Quick guidelines for S3, DynamoDB, RDS, CloudWatch

• npx vitest run ✅ / ❌
• npm run build ✅ / ❌

For Rule PRs

• Has description field in frontmatter
• Under 100 lines
• No overlap with existing rules
• Tested with npx ai-nexus test "<prompt>"

[JSK9999]

Thanks for the contribution — the AWS skill looks solid and follows best practices well.

A few things:

1. mongodb.md is already merged in Add MongoDB aggregation and optimization guidance to database skill #57 — please remove it from this PR.
2. Closes Add Testing Frameworks skill rule (Jest/Vitest/Pytest) #44 should be Closes Add AWS/Cloud skill rule #3 — Add Testing Frameworks skill rule (Jest/Vitest/Pytest) #44 is Testing Frameworks, Add AWS/Cloud skill rule #3 is the AWS skill issue.
3. database.md — looks like just a trailing newline change. Intentional? If not, can drop it.

Once cleaned up, I'll merge.