ci(aws): run aws-featured tests for core and keycast in CI

[sergey3bv]

Summary

• Adding explicit AWS-feature test coverage in CI

Avoid naming corporate partners, customers, or other sensitive external brands in this PR title or body. Use generic descriptors unless a maintainer explicitly approves the public reference.

Motivation

• A follow-up for Add AWS KMS support and document KMS provider selection #100

Related Issue

• Closes ci(aws): run AWS-featured KMS tests explicitly in CI #118

Testing

• cargo test --workspace --verbose
• cargo clippy --workspace --all-targets --all-features -- -D warnings -A deprecated
• cargo fmt --all -- --check
• Manual verification completed

Visuals

• UI/web change with screenshots/video attached
• No visual change
• Visuals and text avoid sensitive external brand or partner names unless explicitly approved