engram-core 0.19.0

AI Memory Infrastructure - Persistent memory for AI agents with semantic search
Documentation
## Description

Brief description of the changes in this PR.

## Type of Change

- [ ] Bug fix (non-breaking change that fixes an issue)
- [ ] New feature (non-breaking change that adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)
- [ ] Documentation update
- [ ] Performance improvement
- [ ] Code refactoring
- [ ] Test update

## Related Issues

Fixes #(issue number)

## Changes Made

- Change 1
- Change 2
- Change 3

## Testing

- [ ] I have added tests that prove my fix/feature works
- [ ] All new and existing tests pass (`cargo test`)
- [ ] I have run `cargo clippy` with no warnings
- [ ] I have run `cargo fmt`

## Documentation

- [ ] I have updated the documentation accordingly
- [ ] I have added doc comments to new public APIs

## Checklist

- [ ] My code follows the project's style guidelines
- [ ] I have performed a self-review of my code
- [ ] I have commented my code where necessary
- [ ] My changes generate no new warnings
- [ ] I have checked my code for potential security issues

## Screenshots (if applicable)

## Additional Notes

Any additional information reviewers should know.