refactor: migrate math and logic nodes to NodeDefinition interface and add comprehensive math unit tests

docs: add ZFS architectural analogy and update future improvements with human interaction layer and state history concepts

refactor: modularize engine architecture by splitting core evaluation, topology, and registry logic into a structured directory hierarchy

refactor: reorganize codebase with consistent section headers and improved logical grouping of engine functions and types

feat: implement topological graph engine with parallel execution, watchdog timeouts, and error isolation

feat: implement functional graph engine with topological sorting, concurrent execution, and watchdog-based error isolation

Merge branch 'main' of https://github.com/zuma/litegraph-fp

Initial commit

Expand README with functional programming benefits

Initial commit