chore: update readme and REGION setting

[drduhe]

Issue #, if available: n/a

Summary

• Auto-detect AWS region -- Replaced the hardcoded REGION = "us-west-2" in src/config.ts with a resolveRegion() function that follows the standard AWS precedence chain: AWS_REGION env var, AWS_DEFAULT_REGION env var, ~/.aws/config [default] profile, then falls back to us-west-2. No new dependencies; reuses existing imports.
• README overhaul -- Rewrote README.md with a features overview, architecture table, usage guides for all four workflows, annotated project structure, configuration reference (including the new region auto-detection docs), and updated resource links. Removed outdated CloudScape reference and fixed the duplicate clone command.

Checklist

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• Code changes are compact and well-structured to facilitate easy review
• Changes are documented in the README.md and other relevant documentation pages
• PR title and description accurately reflect the changes and are detailed enough for historical tracking
• PR contains tests that cover all new code and the code has been manual tested
• All new dependencies are declared (if any), and no unnecessary libraries are added
• Performance impacts (if any) of the changes are evaluated and documented
• Security implications of the changes (if any) are reviewed and addressed
• I have read the Contributing Guidelines and agree to follow the Code of Conduct

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[devinglauner]

LGTM