Add Python stub file generation with documentation parsing

[andrewleech]

Summary

This PR adds comprehensive Python stub file (.pyi) generation for the LVGL MicroPython bindings, providing full IDE support with autocompletion, type hints, and rich documentation.

Key Features:

• Rich Documentation: Automatic extraction from 1400+ LVGL functions
• IDE Integration: Full autocompletion and type hints (.pyi files)
• Separate Build: Doesn't slow down main MicroPython builds
• Smart Formatting: Bullet points, text wrapping, proper Python conventions
• Source Navigation: File:line references to original C implementation
• Fast Parallel Processing: 6 seconds vs. minutes (uses all CPU cores)

The implementation includes:

1. Stub Generation: Creates .pyi files with proper Python type hints
2. Documentation Parsing: Extracts Doxygen comments from C headers using parallel processing
3. Smart Parameter Handling: Converts obj to self for class methods
4. Performance Optimization: Processes 209 header files in ~6 seconds using all CPU cores
5. Source References: Adds file:line references for navigation to C implementation

Testing

Tested on Unix port with full stub generation:

• Processes 209 LVGL header files using parallel processing
• Extracts documentation from 1423 functions
• Generates type hints for 41 widget classes and 64 enums
• Produces comprehensive .pyi files for IDE consumption

The generated stubs provide full autocompletion and documentation in modern Python IDEs like VS Code, PyCharm, etc.

Trade-offs and Alternatives

Trade-offs:

• Adds ~6 seconds to generate full documentation (but as separate optional target)
• Increases repository size slightly with documentation files

Alternatives considered:

• External documentation parsing libraries (rejected to minimize dependencies)
• Manual stub file maintenance (rejected due to maintenance burden)
• No documentation extraction (rejected as it provides significant developer value)

The implementation uses custom regex-based Doxygen parsing to avoid external dependencies while providing exactly the functionality needed for LVGL's documentation format.

[andrewleech]

Thanks for the feedback, though I must admit you caught me off guard. I left this PR in draft because I intended to do a manual cleanup before prompting for discussion.

Yes this has been put together with significant assistance from Claude Code AI, I have been getting very high quality code design acceleration with it both professionally and on open source work.

This PR is actually the first in a string of improvements I've been intermittently working on; these stubs after intended to help developers certainly, but I also used them as an input for Claude to reference in a follow up branch to fix and modernise the examples and bring them all up to valid v9 syntax.