0.6.6 release

[mxfactorial]

added

• organized traits into dedicated modules with feature flags
• implemented conditional compilation for optional traits (optics, projection, manifold)
• tensor test suite comparing mathematical representation and performance with geonum

changed

• refactored codebase for improved maintainability and organization
• moved primary types into separate modules (geonum.rs, multivector.rs, dimensions.rs)
• reduced lib.rs size
• fixed Clippy lints and warnings throughout codebase
• new benchmark numbers in README