new feature: publish Python bindings to Anaconda Defaults

[Xuanwo]

Feature Description

Publish the OpenDAL Python binding as a Conda package in Anaconda Defaults (main) so users can install it with:

conda install main::opendal

This should cover the platforms supported by the Python binding and the Python versions supported by its released package metadata.

Problem and Solution

The Python binding is available on PyPI, but opendal is currently absent from Anaconda Defaults. This also blocks opendalfs from being published to main, because opendalfs has a runtime dependency on opendal and a clean Conda environment cannot resolve that dependency today.

A practical path is:

1. Complete the conda-forge packaging tracked by Python bindings: publish on conda-forge #4391.
2. Request adoption of the resulting feedstock into Anaconda Defaults, following the process documented by AnacondaRecipes/aggregate or the current Anaconda package-request process.
3. Verify the package from a clean environment on each supported Defaults platform.
4. Document ownership and automate version updates for future OpenDAL Python releases.

Acceptance criteria:

• A maintained Conda recipe/feedstock builds the released Python binding from source with matching Python support and runtime metadata.
• Packages are available from Anaconda Defaults for the supported platform set, including linux-64, linux-aarch64, osx-64, osx-arm64, and win-64 where the dependency set supports them.
• conda install main::opendal succeeds in a clean environment.
• python -c "import opendal" succeeds after installation.
• The feedstock has documented maintainers and an update path for future tagged releases.

Additional Context

• Existing conda-forge request: Python bindings: publish on conda-forge #4391
• Downstream request blocked on this package: Publish opendalfs to Anaconda.org fsspec/opendalfs#61
• Current opendalfs requirement: opendal>=0.47.5,<0.48