Fix memory leak and add Cython 3.0 support

[niko-zvt]

Summary

This PR fixes two critical issues in pysbpl:

1. Memory leak (~500 MB per operation) caused by missing destructors
2. Cython 3.0 incompatibility causing compilation failures

Both fixes must be applied together because the memory leak fix adds C++ operators that require the Cython 3.0 migration to compile correctly.

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Problem 1: Memory Leak

Issue

Each pathfinding operation leaks ~300-500 MB of virtual memory because C++ objects are created with new but never freed. Over thousands of operations, this accumulates 10-25 GB and eventually crashes with MemoryError.

Root Cause

Missing __dealloc__() methods in Cython wrapper classes:

• EnvironmentNAVXYTHETALAT: Leaks C++ environment object (~300 MB) and malloc'd mapdata
• ARAPlanner: Leaks C++ planner object (~200 MB)

Solution

Added proper __dealloc__() destructors following Cython documentation.

Problem 2: Cython 3.0 Incompatibility

Issue

The setup.py uses deprecated Cython.Distutils.build_ext API from Cython 0.x, which fails to process the # distutils: language = C++ directive correctly. This causes compilation errors:

Error compiling Cython file:
pysbpl/sbpl.pyx:68:23: Operation only allowed in c++

Root Cause

Cython.Distutils is deprecated since Cython 3.0. The C++ language directive is ignored, causing compilation in C mode. C++ operators (new, del) are only available in C++ mode.

Solution

Migrated to modern Cython.Build.cythonize() API:

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Backward Compatibility

100% backward compatible for users:

• No API changes
• No changes to method signatures
• No changes to public interfaces
• Existing code continues to work identically

Build requirement:

• Requires Cython == 3.0.11 for compilation

List of changes:

• Migrate to Cython 3.0.11 and modern cythonize() API
• Add pyproject.toml to fix build isolation issues
• Implement proper dealloc() methods to prevent memory leaks
• Remove deprecated Cython.Distutils and -Wstrict-prototypes workaround
• Update to Python 3 syntax (print statements)
• Add macOS troubleshooting for rpath issues
• Bump version to 0.0.2

[niko-zvt]

@poine @schmittlema
Hi everyone, I ran into a memory leak issue when running the library in multiprocessing mode with hundreds of calls. I’ve implemented a fix that resolves the problem in my tests. I’d really appreciate it if you could take a look - happy to make any adjustments if needed.