By: lcnbr <im@lcnbr.ch>
Make DOT input support optional Keep DOT parsing enabled by default through the dot feature. Consumers that construct graphs programmatically can disable default features and omit the DOT parser. Gate the Rust parse module and Python DOT constructors together; the programmatic Python Graph and Sampler APIs remain available. Validation: default library and triangle tests pass (35 tests), as do the no-default library and triangle tests (34 tests). Benchmarks compile, and Python API checks pass with and without DOT on Python 3.13. Dependency trees confirm no dot-parser in either no-default configuration.