US-1: IAM Identity Center Module

[nnthanh101]

As a platform engineer managing 30+ AWS accounts,
I want a Terraform module that provisions permission sets, account assignments, and JIT access with audit trails,
So that I can enforce least-privilege across all accounts with SOX Section 404 compliance.

Acceptance Criteria:

• terraform validate PASSED
• terraform plan shows expected resources (permission sets, assignments, groups)
• .tftest.hcl tests PASSED (>=3 test cases: basic, ABAC, JIT)
• Checkov scan: zero HIGH/CRITICAL
• Infracost: $0 (IAM Identity Center is free)
• Examples: basic/, complete/, external-idp/
• README with usage, inputs, outputs tables

INVEST Score: I=5 N=4 V=5 E=4 S=4 T=5 = 27/30