wasm compatibility: switch from std:time to chrono crate

[anotherstarburst]

Pull Request

Description

A clear and concise description of what this PR does.

The crate was failing on my wasm-application due to std::time not being supported. I've switched out std::time to use chrono instead to be cross-compatible with more environments.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Security enhancement

Related Issues

Fixes #(issue number)
Closes #(issue number)
Related to #(issue number)

Changes Made

• Adds chrono as a dependency with wasmbind and serde features.
• Replaces use of std::time for validation_timestamp with chrono::Utc::now().timestamp().
• Add validation timestamp test for ValidationEngine

Code Quality

• Code follows the project's style guidelines
• Self-review of the code has been performed
• Code has been commented, particularly in hard-to-understand areas
• No new warnings or errors are introduced

Testing

• Tests have been added/updated for the changes
• All existing tests pass
• New tests cover the changes made
• Tests have been run locally and pass

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• Security tests added/updated
• Attack pattern tests added/updated

Security Considerations

• This change affects security detection
• This change involves new attack patterns
• This change has been tested against known attack vectors
• Security implications have been documented

Security Testing

• Tested against prompt injection attacks
• Tested against jailbreak attempts
• Tested against Unicode attacks
• Tested against false positives/negatives
• Performance impact assessed

Documentation

• Documentation has been updated
• README.md updated (if applicable)
• API documentation updated (if applicable)
• Examples updated (if applicable)
• CHANGELOG.md updated

Breaking Changes

• This PR contains breaking changes
• Breaking changes are documented
• Migration guide provided (if applicable)

Performance Impact

• No performance impact
• Performance improvement
• Performance regression (documented and justified)

Checklist

(fun fact - this duplicates some of the checklist items from above...)

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published

Additional Notes

Any additional information that reviewers should know.

Screenshots (if applicable)

Add screenshots to help explain your changes.

Reviewer Notes

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[anotherstarburst]

Note, I did run

cargo test
cargo test --features tracing
cargo clippy
cargo fmt

per the contribution requirements, but the project doesn't pass even before this PR. I've made sure my changes pass fine - but didn't want to bloat the PR with a bunch of other changes that fix the pre-existing issue :)