gen/gen_mpy: Add Python stub file generation for IDE support.

Extends the LVGL bindings generator to automatically create Python stub
files (.pyi) that provide type hints and enable IDE autocompletion for
LVGL MicroPython bindings.

Features:
- Type mapping from C types to Python type hints
- Single stub file with all widgets, functions, enums, and constants
- Detailed documentation header with content statistics

The generated lvgl.pyi file includes 40+ widget classes, 300+ functions,
and comprehensive type information for better development experience.

Include C function names, location and description in Python stub docstrings.
The docstrings include a "C function: <name>" line before the
"Source: <file>:<line>" reference. For example:
- Python method `delete()` shows "C function: lv_obj_delete"
- Python method `add_flag()` shows "C function: lv_obj_add_flag"

Create a proper Python package structure for LVGL type stubs:
- Create stubs/pyproject.toml with setuptools-scm versioning
- Add stubs/lvgl-stubs/ package directory with __init__.py and py.typed
- Update gen_mpy.py to output stubs to package directory by default
- Add .gitignore to exclude generated .pyi files but include package structure
- Update README.md with comprehensive IDE support documentation

Signed-off-by: Andrew Leech <andrew@alelec.net>

Author: pi-anl

.gitignore

@@ -6,3 +6,17 @@ yacctab.py
 *.bak
 .history
 .vscode
+
+# Python cache files
+__pycache__/
+*.pyc
+*.pyo
+*.pyd
+
+# Build artifacts
+build/
+*.pp
+*.pp.c
+
+# Test files
+test_*/

README.md

@@ -507,3 +507,66 @@ print('\n'.join(dir(lvgl.btn)))
 ...
 ```
 
+## IDE Support and Type Stubs
+
+For better development experience with IDEs (VS Code, PyCharm, etc.), this repository includes Python type stubs that provide autocompletion, type checking, and documentation hints.
+
+### Installation
+
+The type stubs are automatically generated during the build process and packaged for easy installation:
+
+#### Development Installation (recommended)
+
+For development with the latest stubs:
+
+```bash
+pip install -e /path/to/lv_binding_micropython/stubs
+```
+
+#### From Built Package
+
+After building and packaging:
+
+```bash
+pip install lvgl-stubs
+```
+
+### Features
+
+Once installed, your IDE will automatically provide:
+
+- **Autocompletion** for all LVGL functions, methods, and properties
+- **Type checking** with mypy and other type checkers  
+- **Function signatures** with parameter names and types
+- **Documentation strings** extracted from LVGL C headers
+- **Source location references** to help navigate LVGL documentation
+
+### Building Stubs
+
+The stubs are automatically generated when running the binding generation:
+
+```bash
+# Build with automatic stub generation
+make USER_C_MODULES=/path/to/lv_binding_micropython/micropython.cmake
+
+# Or generate stubs manually
+cd gen
+python gen_mpy.py --stubs /path/to/output/dir [other options...]
+```
+
+The generated `lvgl.pyi` stub file contains type definitions for:
+- All LVGL widget classes (buttons, labels, sliders, etc.)
+- Module-level functions and constants
+- Enum definitions with proper typing
+- Struct types with documented fields
+- Callback function signatures
+
+### Package Structure
+
+The stubs are packaged in `stubs/` directory with:
+- `pyproject.toml` - Package configuration with setuptools-scm versioning
+- `lvgl-stubs/` - Python package containing type stubs
+- `lvgl-stubs/__init__.py` - Package initialization
+- `lvgl-stubs/py.typed` - Marks package as typed
+- `lvgl-stubs/lvgl.pyi` - Generated type stubs (git-ignored)
+